Question

Find x and y
x+y=5
x=y+7

Answer 1

1st equation: x +y =5

2nd equation: x = y +7

replace x in 1st with 2nd

y +7 +y =5

2y+7 =5

2y =-2

y = -1

now replace y in 2nd with -1

x = -1 +7

x = 6

answer:

x = 6

y = -1