Answer:
x=7
y=8
(x+y)= 15
(x-y)= -1
Explanation:
let x and y be the numbers
x + y = 15 ------ 1
2x - y = 6 ------ 2
add both equation 1 and 2
3x = 21
x = 21\3
x=7
subtitute 7 for x in equation 1
7 + y = 15
y = 15-7
y=8
The first number x = 7
The second number y = 8
thus x + y = 7 + 8 = 15
x - y = 7 - 8 = -1