# R1

## QUESTION: The ratio of the ages of Kemah compared to Bob and Deborah is 1∶2∶4. Deborah is 21 years older than Kemah. Work out the ages of Kemah, Bob, and Deborah.

ANSWER: We know that difference between Deborah’s and Kemah’s ages is 21. Looking at the ratio, Kemah has 1 part and Deborah has 4, meaning that the difference between them (21 years) constitutes 3 parts in the ratio. Therefore, we get that

$\text{1 part }=21\div 3=7$

Kemah, Bob, and Deborah have 1, 2, and 4 parts in the ratio respectively. So, we get that

$\text{Kemah’s age }=1\times 7=7$

$\text{Bob’s age }=2\times 7=14$

$\text{Deborah’s age }=4\times 7=28$