Question

A is twice as old as B. B is 1/3 as old as C. The sum of ages of A, B, and C is42 years. Find the sum of the ages of A and B.

• A. 21 years
• B. 23 years
• C. 15 years
• D. 12 years

Answer 1

Answer:

A. 21 years

age of $C=x$

age of $B=x/3$

age of $A=2x/3$

sum of age of $A,B,C$

$\frac{2x}{3}+\frac{x}{3}+x=42$

$\frac{2x}{3}+\frac{x}{3}+\frac{3x}{3}=42$

$\frac{2x+x+3x}{3}=42$

$6x=42\times3$

$x=\frac{126}{6}=21$

age of A and B $=\frac{2x}{3}+\frac{x}{3}=\frac{2\times21}{3}+\frac{21}{3}=14+7=21$