Respuesta :

Answer: [tex]\frac{21}{4}[/tex]

Step-by-step explanation:

Multiply each side by 2 to get rid of the fraction on the right side. That basically gets rid of the 1/2 and the 2.

Youre now stuck with 2x + y = 21. They gave us y which is 2x. 2x + 2x = 4x

You now have 4x = 21

Divide each side by 4 to get x = 21/4

The answer is 21 over 4