4x+3y=13 solve by using substitution method. y=-x/4

Subsitute - x/4 for y

4x+3y=13

4x+3 (-x/4) = 13

4x-3x/4=13

times both sides by 4 because we hate fractions

16x-3x=52

13x=52

divide both sides by 13

x=4

sub back

y=-x/4

y=-4/4

y=-1

(x, y)

(4,-1)

the solution is (4,-1)