Answer :
Hello!
[tex]\large\boxed{x = 15}[/tex]
[tex]\frac{5}{10}= \frac{10}{5+x}[/tex]
Solve for x by cross multiplying:
[tex]5*(5 + x) = 10 * 10[/tex]
Distribute:
[tex]25 + 5x = 100[/tex]
Subtract 25 from both sides:
[tex]5x = 75[/tex]
Divide both sides by 5 to entirely isolate for x:
[tex]5x/5 = 75/5\\\\x = 15[/tex]