I think its D.

Solve, using the substitution method.

2x + 4y = 16
x – 7 = – 4y

A. (0,-7)

B. (0. 7/4)

C. (9, -1/2)

D. (17, -5/2)

Question

I think its D. 

Solve, using the substitution method.
 
2x + 4y = 16
x – 7 = – 4y
 
 
 A. (0,-7)
 
 
 B. (0. 7/4)
 
 
 C. (9, -1/2)
 
 
 D. (17, -5/2)

anonymous · Answer

I'm going to add 7 to both sides of the second equation: x = 7 - 4y.

Now I plug it into the first: 2 [ 7 - 4y ] + 4y = 16.
                                      14 - 8y + 4y = 16
                                      14 - 4y = 16
                                       7 - 2y = 8
                                       -1 = 2y
                                       -1/2 = y.

The only choice with -1/2 is C.

pinksapphire · Answer

Yes, @TurtleMuffin is right.

anonymous · Answer

i'm always late.

anonymous · Answer

I can also multiply the entire second equation by a -1: -x + 7 = 4y.

Now I recognize that my first equation already has a 4y in it!

So I just plug it in directly with no distribution involved: 2x + [ -x + 7] =16

Then I simplify: x + 7 = 16
                       x = 9.