Răspuns:
Explicație pas cu pas:
18a)
1 + 1/3 = 4/3
1/(4/3) = 3/4
1 + 3/4 = 7/4
1 / (7/4) = 4/7
100 - 4/7 = 700/7 - 4/7 = 696/7
____________
18b)
1 + 1/2 = 3/2
1/(3/2) = 2/3
1 + 2/3 = 5/3
1/(5/3) = 3/5 = 0,6
100 - 0,6 = 99,4
________________________
19.
(a + b)/2 = 26/5
a + b = 52/5
a = b*35/17
35b/17 + b = 52/5
35b/17 + 17b/17 = 52/5
52b/17 = 52/5
b = 52/5 *17/52 = 17/5
a = 52/5 - 17/5 = 35/5 = 7
