А) (2-17/12):(3/8-1/6)* 3 1/4= 9,1
1) 2-17/12=1 12/12 - 1 5/12 = 7/12
2) 3/8-1/6=9/24 - 4/24 = 5/24
3) 7/12 : 5/24 = 14/5
4) 14/5 * 3 1/4 = 14/5 * 13/4 = 91/10=9,1
б) (7/10-2/5)*(1/4+5/6):6 1/2 = 1/20
1) 7/10-2/5= 7/10-4/10=3/10
2) 1/4+5/6=3/12+10/12=13/12
3) 3/10 * 13/12 = 13/40
4) 13/40 : 6 1/2= 13/40 : 13/2 = 1/20