x - 1 / 5 = 5 - x / 2 + 3 * x / 4 ;
x * 20 - 1 / 5 * 20 = 5 * 20 - x / 2 * 20 + 3 * x / 4 * 20 ;
20 * x - 4 = 100 - 10 * x + 15 * x ;
20 * x - 4 = 100 + 5 * x ;
20 * x - 5 * x = 100 + 4 ;
15 * x = 104 ;
x = 104 /15
