I don't know how to solve this question

Question

I don't know how to solve this with work and explanation. Morgan uses 1/4 of her supply of raisins to make trail mix and 3/8 of her sully of raisins to make cookies. If Morgan uses 5 pounds of rising, how Manu pounds of raisins are in her supply?

Answer 1

x represents the starting amount

 

5 = 3x/8 + x/4

40 = 3x + 2x     multiply both sides by LCD, 8

40 = 5x

 

Can you solve for x and answer?