какие пропорции верны
а7/11=63/99
б4/8=20/40
в11/13=33/39
г5/7=25/35

7 / 11 = (7 * 9) / (11 * 9) = 63 / 99

4 / 8 = (4 * 5) / (8 * 5) = 20 / 40

11 / 13 = (11 * 3) / (13 * 3) = 33 / 39

5 / 7 = (5 * 5) / (7 * 5) = 25 / 35

Все верны.