I need help figuring out this equation using the substitution method. I would appreciate a step-by-step procedure to base off of.

Question

2x + 3y = 7 and x - 2y = -7

 

I need to solve for Y

I need help figuring out this equation using the substitution method. I would appreciate a step-by-step procedure to base off of

Answer 1

Hi Xavier,

 

The plan is to solve for X or for Y in one equation and then substitute that value in the other equation.

 

Let's solve for X in the second equation:

 

x - 2y = -7

 

Add 2y to each side--> x = -7 + 2y

 

Now substitute -7 + 2y for x in the first equation--> 2(-7 + 2y) + 3y = 7

 

Distribute 2 over the contents of the parentheses--> -14 + 4y + 3y = 7

 

Add the "y" terms and add 14 to both sides--> 7y = 21

 

Divide both sides by 7--> y = 3

 

Plug this into the second equation--> x - 2(3) = -7

 

x - 6 = -7

 

x = -1

 

Plug these values into the first equation to make sure they work.

 

Have fun.

 

Dan