x - y = 3
x = 3 + y
x -3 = y
y = x-3
put it in 1st equation
2x +y = 15
2x + x - 3 = 15
3x - 3 = 15
3x = 15+3 = 18
x = 18/3 = 6
x = 6
Answer:
Step-by-step explanation: