To do solve this you must isolate x. First subtract 16 to both sides (what you do on one side you must do to the other). Since 16 is being added to x, subtraction (the opposite of addition) will cancel it out (make it zero) from the left side and bring it over to the right side.
x + (16 - 16) = 24 - 16
x = 8
Check:
8 + 16 = 24
24 = 24
Hope this helped!
~Just a girl in love with Shawn Mendes