Suppose that x = 2-t and y = 4t+7.

Question

a. If x=7, what is y?
b. If x=-3, what is y?
c. Find y in terms of x.

I don't know how to solve this, since x and y are in different equations. Could you please walk me through it?

Thanks!

Answer 1

t = 2 - x from the first equation
so
y = 4 (2-x) + 7
y = 8 - 4 x + 7
y = 15 - 4 x
You can do it now.

Answer 2

I automatically did the last quesion but you are probably supposed to figure it out the hard way step by step:
When x = 7
7 = 2 - t
so t = 2 - 7 = -5
then
y = 4 t + 7
y = 4(-5) + 7
y = -20 + 7
y = -13
Now I would have just said:
y = 15 - 4x
y = 15 -4*7
y = 15 - 28
y = -13 again
Now you can do it for x = -3

Answer 3

Thanks!

Answer 4

is x=-3 then you plug it in to the first one and you get -3=2-t which is t=5 and then you plug 5 into the t in the equation y = 4t+7 and you get the answer which is y=27.