Question 12915
This is very basic and perhsps that is why no one is even touching this prolem. U should take the terms of x on one side ( & i hope u know that u need to change the signs wen u do so) and then solve for x 

in this case -7A + 12A  = 65 
5A = 65 
thus A = 13

But u really need specific lessons for upgrading ur knowledge