Help with my childs homework!

The sum of two intergers is -41. The greater number minus the lesser number is 13. Which is the greater of the two numbers?

let the numbers be x and y,  the big one is x

x+y=-41     (1)

x-y = 13     (2)

find  x

add the 2 equations

x+y     +x-y  =  -41+13

the ys cancel out

2x= -28

x = -14

Check

find y from equ (1)      

-14+y=-41

so y= -41+14 = -27

sub into equation (2)     -14 - - 27 = -14 + 27 = 13    excellent

The biggest number is   -14

Its the same person here just can you explain it to me a little bit more of how to work this problem..