вычислите: а) 1/5+3/4+1/5+1/4 б)11/12+7/10+3/100+1/12 в)12/17+15/24+3/8+5/17 г)3/7+5/9+4/9+4/7

Вычислим значения выражений: 

а) 1/5 + 3/4 + 1/5 + 1/4 = (1/5 + 1/5) + (3/4 + 1/4) = (1 + 1)/5 + (3 + 1)/4 = 2/5 + 4/4 = 2/5 + 4/4 = 2/5 + 1 = 1 2/5; 

б) 11/12 + 7/10 + 3/100 + 1/12 = 12/12 + 70/100 + 3/100 = 1 + 73/100 = 1 73/100; 

в) 12/17 + 15/24 + 3/8 + 5/17 = (12 + 5)/17 + (15 + 3 * 3)/24 = 17/17 + (15 + 9)/24 = 1 + 24/24 = 1 + 1 = 2; 

г) 3/7 + 5/9 + 4/9 + 4/7 = (3 + 4)/7 + (5 + 4)/9 = 7/7 + 9/9 = 1 + 1 = 2.