find two mixed numbers so that the sum is 16 and the difference is 15.

Question

find three mixed numbers so that the least number is 5 1/5.

Answer 1

x + y = 16
x - y = 15

add the two equations

2x = 31 so x= 31/2 or 15 1/2

So then y = 1/2

Answer 2

so why is y= 1/2?