Question

which of these shows results of using the first equation to substitute for y in the second equation then combine like terms y=2x 2x+3y=16
A.5y=16
B.4x=16
C.8x=16
D.5x=16
I think it is C

Answer 1

2x+3(2x)=16
2x+6x=16
8x=16
you are absolutely right

Answer 2

Answer:The correct option is (C). $8x=16.$

Step-by-step explanation:  The given system of equations is

$y=2x~~~~~~~~~~~~~~~~~~~~~~~~(i)\\2x+3y=16~~~~~~~~~~~~~~~~(ii)$

We are given to to choose the correct option that shows results of using the first equation to substitute for y in the second equation then combine like terms.

From equation (i), we have

$y=2x.$

Substituting the value of 'y' from here in equation (ii), we get

$2x+3y=16\\\\\Rightarrow 2x+3\times 2x=16\\\\\Rightarrow 2x+6x=16\\\\\Rightarrow 8x=16.$

Therefore, the correct result is $8x=16.$

Thus, option (C) is correct.