［51 -（18 3/4 - 1÷ 8/15 ）× 1 23/25］÷ 0.62
=［51 -（150/8-15/8)*48/25]/0.62
=(51-135/8*48/25)/0.62
=(255/5-162/5)/0.62
=93/5*100/62
=30