how do you solve y = x + 5 and 3x + y = 25

Question

y=x+5

3x+y=25

(this is the initial equation)

Answer 1

Since by the first equation, we know y in terms of x, substitute that for y in the second equation:

3x+y=25 -> 3x+x+5=25 -> 4x=20 -> x=5, so y=5+5=10

Answer 2

Y-5=x

3(y-5)+y=25

3y-15+y=25

4y-15=25

4y=40

Y=10