Math Help please help me?

2007-12-29 4:28 am
PLEASE HELP me with these math problems if you want ten points of course :)

5x + 28 = 153
3(2r - 5) + 8(r + 2)
w ? (-2) = 14
Fencing Thirty-six sections of fencing,
all the same length, are joined to form
a fence 180 m long. How long is each
section of fencing?

How are the rules for
solving inequalities similar to those for
solving equations? How are they different?
y - 6 , 9

ok thats all the questions sorry there so long but please please help me Im desperete

回答 (7)

2007-12-29 4:52 am
✔ 最佳答案
5x + 28 = 153
Isolate the variable by reversing the order of operations. In other words: subtract 28 from both sides of the equation, then divide the value of 5x by 5.
3(2r - 5) + 8(r + 2)
w ? (-2) = 14
Is this one equation? What does the question mark stand for after w? You can combine like terms in 3(2r - 5) + 8(r + 2). The first step would be 3*2r - 3*5 + 8*r + 8*2. Can you take it from there?

Fencing Thirty-six sections of fencing,
all the same length, are joined to form
a fence 180 m long. How long is each
section of fencing? 180/36 m

How are the rules for
solving inequalities similar to those for
solving equations? How are they different?

You solve for the variable by reversing the order of operations, but any time you cancel a negative coefficient
(-3x/-3 = +x), the direction of the inequality changes. So, if
-3x < 9, x > -3

y - 6 , 9
I don't know what this represents.

ok thats all the questions sorry there so long but please please help me Im desperete
2007-12-29 5:07 am
1)
5x + 28 = 153
5x + 28 - 28 = 153 - 28
5x = 125
5x/5 = 125/5
x = 25

2)
3(2r - 5) + 8(r + 2)
= 6r - 15 + 8r + 16
= 14r - 15 + 16
= 14r - (-1)
= 14r + 1

3)
w(-2) = 14
-2w = 14
-2w/-2 = 14/-2
w = -7

4)
180/36
= 5 m

5)
I don't know

6)
y - 6 , 9 ???
Do you mean: y - 6 = 9
y - 6 = 9
y = 15
2007-12-29 4:45 am
On the 3rd problem, if you meant w / (-2) = 14, then you want to do the opposit of dividing by -2 which is multiply by -2
you end up with w=-28


On your last problem, the rules are the same except when you multiply (or divide) by a negative number.

since you solve y - 6 = 9 by adding 6 to both sides to get y=15
you do the same to solve y - 6 < 9 to get y<15
2007-12-29 4:43 am
5x + 28 = 153
5x = 153-28 = 125
x= 125/5 = 25
-----------------------
3(2r - 5) + 8(r + 2)
6r -15 +8r +16
14r +1
-----------------------
w ? (-2) = 14 I dunno what you mean here by the ?
-2w = 14
w = -7
---------------------
36 * l = 180
l = 180/36
l = 5
-----------------------
I dont know the last one
2007-12-29 4:38 am
5x + 28 = 153
easy, just subtract the 28 from both sides.
That then leaves you with 5x = 153 - 28
That goes to 5x=125
Then you just solve for X, and do so by dividing the 5.
Then answer is 25.

3(2r-5) + 8(r+2)
First distribute the number outside of the parenthesis into the parenthesis by multiplying.
It goes to, (6r-15) + (8r+16)
Then add like terms together
14r+1
But if you're solving for r, then the answer would be -1/14

I don't really understand what you mean by the 3rd problem, but w(-2)=14 would be w=-7, because you divide both sides by negative 2 and end up with -7.

The fencing problem is 180/36, which equals 5. Each section would be 5 m long.

Not quite sure about the last problem, sorry :\
2007-12-29 4:35 am
5x + 28 = 153
5x = 125
x = 25

3(2r - 5) + 8(r + 2)
6r - 15 + 8r + 6
14r -9

w ? (-2) = 14
w = -7

if there are 36 sections in a 180m long fence, divide 180 by 36 to get 5: therefore each section is 5m long.

treat the inequality sign like and equal sign and solve the same way, the only rule is that when you divide by a negative number reverse the direction of the sign.

y - 6, 9
is this y-6=9?
then it would be:
y = 15

hope this helps!
2007-12-29 4:31 am
x equals 25


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