Use substitution to solve the system of equations.

x=2y-5
x+3y=10

Question

Use substitution to solve the system of equations.

x=2y-5
x+3y=10

marissalovescats · Answer

Oh by substitution okay '

So it says: x=2y-5

This means we plug that in for x in the second equation

marissalovescats · Answer

2y-5+3y=10 

add 5 to both sides: 

2y+3y=15 

2y+3y is 5y so 

5y=15

divide by 5

y=3

marissalovescats · Answer

Since we know y=3 we plug that into: 

x=2y-5

x=2(3)-5 

x=6-5

x=1 



So we solved it. x=1 and y=1

marissalovescats · Answer

y=3* oops typo :P

anonymous · Answer

So because there isn't a multiplication option, you would just add the x equation to the other equation and not multiply? That confuses me sometimes.

marissalovescats · Answer

No you don't have to do any multiplication. Substitution just means put it in place of. 

So since we were given x=2y-5 this means that is what x equals. so in the 2nd equation we just replace x with 2y-5

anonymous · Answer

Thank you :) This helped a lot.

marissalovescats · Answer

You're welcome :)