13) 3 bags of Brand X dog food and 4 bags of Brand Y dog food costs $18,

while 4 bags of Brand X dog food and 3 bags of Brand Y dog food costs

$17. What is the cost of each bag of Brand X?

the cost of brand x dog food is $2

Step-by-step explanation:

Let brand X dog food be represented as A

Let Brand Y dog food be represented as B

3 bags of Brand X dog food and 4 bags of Brand Y dog food costs $18,

3A+4B=18

4 bags of Brand X dog food and 3 bags of Brand Y dog food costs

$17.

4A+3B = 17

3A+4B=18 4A+3B = 17

Using Elimination method

Multiply

3A+4B=18 by coefficient of B in equ ii (3) = 9A+12B=54 4A+3B = 17 by coefficient of B in equ i (4) = 16A+12B=68 subtract equation i from equation ii, since sign is the same in both equations 9A+12B - (16A+12B) = 54-68 open bracket 9A+12B-16A-12B = 54-68 = - 14 9A-16A+12B-12B = - 14 - 7A = - 14 divide both sides by - 7

A = - 14/-7 = 2

Since the brand X dog food is represented as A

the cost of brand x dog food is $2