Помогите решить (3/4-4/5) * 7,8 +(2/3 +4/7 ) * 7/13

Question

Помогите решить (3/4-4/5) * 7,8 +(2/3 +4/7 ) * 7/13

Answer 1

(3/4-4/5) * 7,8 +(2/3 +4/7 ) * 7/13= 83/300

1) 3/4 - 4/5= 15/20 - 16/20= - 1/20
2) 2/3 + 4/7= 14/21 + 12/21= 26/21= 1 5/21
3) - 1/20 * 7,8= -5/100 * 7,8= -0,05 * 7,8= - 0,39
4) 1 5/21 * 7/13= 26/21 * 7/13 = 2/3
5) -0,39 + 2/3= - 39/100 + 2/3= - 117/300 + 200/300= 83/300