17/(3/5+1/4)+(7/8-1/4)*(4/5)

решение

1) 3\5 + 1\4 = 12\20 + 5\20 = 17 \20

2)7\8 - 1\4 = 7\8 - 2\8 = 5\8

3) 5\8 * 4\5 = 1\2

4) 17: 17\20 = 20

5) 20 + 1\2 = 20.5