Substitution

-x + y=-5

3x-5y=9

To subsitute you mean

make one side equal to only one placehloder

so - x+y=-5

make equal to y

add x to both sides

y=x-5

subsitute x-5 for y in second equation

3x-5 (x-5) = 9

3x-5x+25=9

add like terms

-2x+25=9

subtract 25 from both sides

-2x=-16

divide by 2

-x=-8

multiply - 1

x=8

subsitute 8 for x in first equation

y=x-5

y=8-5

y=3

x=8

y=3