The cost of one tub of brownie mix = $12
Explanation:
Step 1 :
Let x represent one tub of cookie mix's cost and y represent one tub cookie mix's cost
Total amount raised by Elaine = $75
Number of cookie mix tub sold by Elaine = 1
Number of brownie mix tub sold by Elaine = 5
This can be represented by the equation
x + 5 y = 75 => x = 75 - 5y
Step 2 :
Total amount raised by Megan = $141
Number of cookie mix tub sold by Megan = 3
Number of brownie mix tub sold by Megan = 8
This can be represented by the equation
3 x + 8 y = 141
Step 3 :
Solving the equations obtained in the above steps we have ,
3 ( 75-5y) +8y = 141
225 - 15y + 8y = 141
-7y = -84 => y = 12
Step 4 :
Answer :
The cost of one tub of brownie mix is $12