If (a + b) : c = 7 : 5, (b + c) : a = 9 : 3 , then (a + c) : b = ?

In these type of questions always note that the total amount/ratio must be same in all conditions.

⇒ (a + b) : c = 7 : 5  = 12 (total)

⇒ (b + c) : a = 9 : 3 = 12 (total)

total equal is already equal,

Therefore,

a = 3 , c = 5 & b = 12 -(3 + 5) = 4

Here,

⇒ (a + c) : b = 8 : 4  = 2 : 1