Математика даю 40 баллов
(2,125*1 15/17-1 7/12):7,25=

(2,125 * 1 15/17 - 1 7/12) : 7,25 = 1/3

1). 2,125 * 1 15/17 = 17/8 * 32/17 = 4

2). 4 - 1 7/12 = 3 12/12 - 1 7/12 = 2 5/12

3). 2 5/12 : 7,25 = 29/12 : 29/4 = 29/12 * 4/29 = 1/3