Ten years ago, A was half of B in age. If the ratio of their present ages is 3 : 4, what will be the total of their present ages ?

\par Let the ages of A and B 10 years ago be x and 2x years respectively.

\frac{x+10}{2x+10} = \frac{3}{4}

4(x + 10) = 3(2x + 10)

2x = 10

x = 5

\par Sum of their present ages = (x + 10) + (2x + 10) = (3x + 20) = 35 years