The system of equations above has solution (x,y).
What is the value of x ?

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