Question

The ratio of Neha's age to that of Jenny is 4:7 and the ratio of Jenny's age to that of Sumita is 4:3. If Sumita is 21 years old, how old is Neha?

Answer 1

$let \: the \: common \: ratio \: be \: 4x \: and \: 3x \\ 3x = 21 \\ x = \frac{21}{3} \\ x = 7 \\ jenny \: age \: = 4x \\ = 4 \times 7 \\ = 28 \: years \\ common \: ratio \: of \: neha \: and \: jenny \: be \: 4x \: and \: 7x \\ 7x = 28 \\ x = \frac{28}{7} \\ x = 4 \\ neha \: age \: = 4 \times 4 \\ = 16 \: years$