13 + x/2 = 3x
=> to solve this first convert 13 and x/2 into like fractions(with same denominators) ...
=> 13 is also 13/1
=> so 13/1 = 13/1 * 2 = 26/2
=> 26/2 + x/2 = 3x => (26+x)/2 = 3x
=> 26 + x = 3x*2
=> 26 = 6x - x
=> 5x = 26
=> x = 26/5
=>x = 5.2
hope it helps !!!!