Răspuns:
Explicație pas cu pas:
Se introduc intregii in fractie
2 4/5 = 14/5
2 7/10 = 27/10
1 3/25 = 28/25
14/5 * (27/10 * 20/63 - 14/15 : 28/25) = 14/5 * (27/10 * 20/63 - 14/15 * 25/28) =
= 14/5*(6/7 - 5/6) = 14/5*(36/42 - 35/42) = 14/5*1/42 = 1/15
____________
b) [(7/15+1/3-1/5).5/4+(1/-1/4) :5/12].2/7
7/15+1/3-1/5 = 7/15 + 5/15 - 3/15 = 9/15 = 3/5
3/5*5/4 = 3/4
1/-1/4 = -4
(3/4 - 4*12/5)*2/7 = (3/4 - 48/5)*2/7 = (15/20 - 192/20)*2/7 = -177/20*2/7= -177/70