Asked by Tika

How do I use substitution to solve the system? Please help Addition and equal key is not working


-5x plus 2y equal 16
y equal 2x plus 7
Answered by Reiny
-5x+2y=16

y = 2x+7

Tika,
Doesn't the 2nd equation tell you what the value of y is ??
Just replace the y in the 2y of the first equation with the value of y in the second.
Give it a try, it is really easy.
Let me know what you got.
Answered by Tika
I'm still lost
Answered by Reiny
first equation:
-5x + 2y = 16
subbing in y = 2x+7
----> -5x + 2(2x+7) = 16
-5x + 4x + 14 = 16
-x = 2
x = -2

now put that back into
y = 2x+7
= 2(-2) + 7 = 3

all done

curious, at what grade level are you taking this?
Answered by Tika
Your question seems a bit sarcastic, but thank you for showing me step by step on how you got the answer. This is college level algebra, and I have always had trouble with algebra. I haven't taken a math course in over 16 years.
Answered by Reiny
Was not meant to be scarcastic, simply trying to figure out the best way to explain it, there are several ways.
Answered by Tika
The question is asking x equals and y equals