Because this is addition, you must reverse the process by (maybe) doing x/3 and 8/1 or 7/1. Cross multiply the numerators and denominators.
Answer:
[tex]x=45[/tex]
Step-by-step explanation:
[tex]7+8=\frac{x}{3}[/tex]
Combine the 7 and 8:
[tex]15=\frac{x}{3}[/tex]
Multiply both sides by 3:
[tex]45=x\\x=45[/tex]
