Answer
Find out the how many of each size bag did you buy .
To proof
Let us assume that the one-pound bags = x
Let us assume that the three-pound bags = y
As given
if you buy 5 bags
than the equation becomes
x + y = 5
As given
a shop has one-pound bags of peanuts for $2 and three-pound bags of peanuts for $5.50
if you buy 5 bags and spend $17
than the equation becomes
2x + 5.50y = 17
2x + 5.50y = 17
than the two equation are
2x + 5.50y = 17 and x + y = 5
mulitply x + y = 5 by 2 and subtracted from 2x + 5.50y = 17
2x - 2x + 5.50 y - 2y = 17 - 10
3.5y = 7
y = 2
put y = 2 in x + y = 5
x = 5 -2
x = 3
Therefore one-pound bags of peanuts bags are 3 and three-pound bags of peanuts bags are 2 .
Hence proved