y=6x and 2x+3y=-20

Question

have to use substitution 

Answer 1

Yes, you have to use substitution. Substitution means that we will replace a variable in one equation with another one. We do this because we can't solve an equation for a single number when there are two variables.

 

y = 6x

2x + 3y = -20

 

We will replace the "y" in the second equation with "6x" because the first equation tells us that the two values are equal.

 

2x + 3(6x) = -20

2x + 18x = -20

20x = -20

x = -20/20

x = -1

 

Now that we know x is -1, we can substitute that back into either equation to solve for "y." I will substitute "-1" for "x" in "y = 6x"

 

y = 6(-1)

y = -6

 

x = -1, y = -6