Mathematics inAcyion 1A (4c and 4d)(15marks!!!quick!!!

2007-12-11 2:24 am

1)Shirley has three types of coins $1-coins $2-coins and $5-coins. The number of$5 -coins is more than the number of $1-coins by 3,while the number of $2-coins is 8 more than twice the number of $5-coins. If Shirley has 97 coins find the total valueof coins
2)Solve the followingt literal equation for x
ax+b÷c=dx
3)Solve the followingt literal equation for x
a(3-x)=b

回答 (1)

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2007-12-14 5:31 am

✔ 最佳答案

1.
Let the number of $1-coins $2-coins and $5-coins be x,y and z,
The number of$5 -coins is more than the number of $1-coins by 3:
i.e. z-x=3 --(1)
the number of $2-coins is 8 more than twice the number of $5-coins:
i.e. y=8+2z --(2)
if Shirley has 97 coins:
i.e. x+y+z =0 --(3)
Sub. (1) & (2) into (3):
(z-3)+(8+2z)+z =97
4z=92
z=23
y=54
x=20
Therefore, Shirley has 20nos. $1-coins, 54nos. $2-coins and 23nos. $5-coins

2. (ax+b)÷c=dx
ax+b=cdx
b=(c-a)x
x= b/(c-a)

3. a(3-x)=b
3-x=b/a
x= 3-(b/a) = (3a-b)/a

參考: my math knowledge

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