Question

how can i solve a system of equations using substitution
x+4y=-15
3x+3y-0

Answer 1

for substitution look at the 2nd equation and rewrite it

3x + 3y = 0

or

3x = -3y

or

x = -y

substitute this into the 1st equation

(-y) + 4y = -15

or

3y = -15

solve for y

when you have y substitute it into either equation to find x

Answer 2

so how do i solve 3y=-15 do i add 3y to both sides

Answer 3

divide both sides of the equation by 3

Answer 4

ok i got y=5 is that correct

Answer 5

not quite it should be y = -5

Answer 6

so looking at the 1st equation and substituting y = -5

x + 4*(-5) = -15

so

x - 20 = -15

whats x..?

Answer 7

oh k i got that one
so how do i do 9x-8y= -6
x-3y=-7 do i do the same and how

Answer 8

so i subtract 20 and -15 right.

Answer 9

i am not sure