The sum of two numbers is 30. The difference between them is -5. Find them.

Question

I can't figure this out please help

Answer 1

Let the two numbers be X and Y

 

X + Y = 30      (1)

 

X - Y = -5        (2)

 

Add equation (1) to equation (2)

 

2X + 0 = 25

 

therefore X = 25/2 = 12.5

 

substitute this value for X in equation (1)

 

12.5 + Y = 30

 

Y = 30 - 12.5 = 17.5