math (eng) thx!!

1. The two consercutive odd numbers are (m + 1) and (m + 3) respectively.

So, the sum of the two consercutive odd numbers

= (m + 1) + (m + 3)

= 2m + 4




2. Let there are x $2 coins,

then (85 - x) is the number of $5 coins

From the given condition,

2x + 5(85 - x) = 275

-3x + 425 = 275

3x = 150

x = 50

So, there are 50 $2 coins,

and 85 - 50 = 35 $5 coins.

equation
let the no.of $2coins are x,$5 coins are y,
x+y=85---------(1)
and
2x+5y=275-----------(2)
By solving the above equations,
from(1), x=85-y -------(3)
sub.(3) into (2), 2(85-y)+5y=275
170+3y=275
3y =105
y=35,x=50

odd number juz larger than m = m+1
two consecutive odd numbers juz larger than m = m+1 and m+3
therefore, sum of two consecutive odd numbers juz larger than m = m+1+m+3 = 2m+4


let number of $2 coins be x
let number of $5 coins be y
lead to 2 equations:
1) 2x+5y = 275
2) x+y = 85

from 2), x = 85 - y --> 3)
sub 3) into 1)
2(85 - y) + 5y = 275
170 - 2y + 5y = 275
3y = 105
y = 35
sub y = 35 into 2)
x = 85 - 35 = 50

there are 50 $2 coins and 35 $5 coins