Solve system of equations using substitution x=7y and 3x+2y=23

Since you know x = 7y

Then you basically plug in 7y in the second equation in place of x

So then you get 3 (7y) + 2y=23

And 3 x 7y = 21y

So now your equation is 21y + 2y = 23

And 21y + 2y = 23y

So now your equation is 23y = 23

Then divide both sides by 23 to get y alone

And you should get y = 1

Now that you know y=1

So plug 1 in place of y in either of the equation

I chose the first one since it is easier

So when you plug in 1,

Your equation is now x = 7 (1)

And 7 x 1 = 7

So x = 7

So the solution is (7, 1)

X=7y

3x+2y=23 plug 7y into this equation's x

3 (7y) + 2y=23 multiply 3 and 7

21y + 2y=23 add 21y and 2y together

23y=23 divide both sides by 23

y=1 then plug y into one of the given equations, either one it doesn't matter but I would use x=7y cause it's easier

x=7 (1)

x=7

so, x=7 and y=1