a, 3/5 x X = 2/7 - 1/4
3/5 x X = 1/28
X = 1/28 : 3/5
X = 5/84
b, x : 4/9 = 2/5 - 1/3
x : 4/9 = 1/15
x = 1/15 x 4/9
x = 4/135
3/5.x = 2/7-1/4
x = 5/84
b) x:4/9 = 2/5-1/3
x = 4/135
3/5 . x = 2/7 - 1/4
3/5 . x = 1/28
x = 1/28 : 3/5
x = 5/84
b) x : 4/9 = 2/5 - 1/3
x : 4/9 = 1/15
x = 1/15 . 4/9
x = 4/135