1,
A . 15 : 25 / 4
= 15 x 4/ 25
= 60 / 25
=12/5
2,
A .X+1/2=3/4
X = 3/4- 1/2
X = 1/4
B . 8/9 - X x 2/ 5 = 2/3
X x 2/ 5 = 8/9 - 2/3
X x 2/ 5 = 2/ 9
X = 2/ 9 : 2/5
X = 5/9
C . X x 2/7 + 11/ 14 x X=1/14
X x (2/7 + 11/ 14 ) = 1/14
X x 15/14 = 1/14
X = 1/14 : 15/ 14
X = 1/15