Answer:
The first step is to replace the value of x from the first equation with x in the second equation:
x=y-7
3x+15y=-1
3(y-7)+15y=-1
3y-21+15y=-1
18y=-1+21
18y=20
y= [tex]\frac{20}{18}[/tex] = [tex]\frac{10}{9}[/tex]
x= [tex]\frac{10}{9}[/tex] [tex]- 7[/tex]
x=[tex]- \frac{53}{9}[/tex]
