вычислите разность 7/8-3/4= 9/10-2/5= 3/5-4/15= 7/8-6/7= 7/12-8/15= 25/39-15/26= 7/15-8/25= 7/45-7/60=

Чтоб выполнить деянья, приведем дроби к общему знаменателю:

1) 7/8 - 3/4 = 7/8 - (3 * 2)/(4 * 2) = 7/8 - 6/8 = (7 - 6)/8 = 1/8;

2) 9/10 - 2/5 = 9/10 - (2 * 2)/(5 * 2) = 9/10 - 4/10 = (9 - 4)/10 = 5/10 = 5/(5 * 2) = 1/2;

3) 3/5 - 4/15 = (3 * 3)/(5 * 3) - 4/15 = 9/15 - 4/15 = 5/15 = 1/3;

4) 7/8 - 6/7 = (7 * 7)/56 - (6 * 8)/56 = 49/56 - 48/56 = 1/56;

5) 7/12 - 8/15 = (7 * 5)/60 - (8 * 4)/60 = 35/60 - 32/60 = 3/60 = 1/20;

6) 25/39 - 15/26 = (25 * 2)/78 - (15 * 3)/78 = 50/78 - 45/78 = 5/78;

7) 7/15 - 8/25 = (7 * 5)/75 - (8 * 3)/75 = 35/75 - 24/75 = 11/75;

8) 7/45 - 7/60 = (7 * 4)/180 - (7 * 3)/180 = 28/180 - 21/180 = 7/180.