Question

if a : b + c = 4 : 5 and b : a + c = 5 : 7.
Find a:b:c

Answer 1

Observe that the figures against b are 9 and 4 .

Find LCM of 9 and 4. This is 36.

Now make figures in both ratios such that figure against b is 36.

Therefore a : b = (Multiply by 4) 5x4 : 9x4 = 20 : 36

                B : c = (multiply by 9) 4x9 : 7x9 =        36 : 63

When figure against b is made same (as b =36 above),

Ratio a : b : c = 20 : 36 : 63

and a :c = 20 : 63