Question

Marc is half as old as Tony and three times as old as Ben. If the sum of their ages is 40, how old is Marc?

Answer 1

Answer:

Marc's age is 12

Step-by-step explanation:

Let

x ----> Marc's age

y ---> Tony's age

z ---> Ben's age

we know that

the sum of their ages is 40

so

$x+y+z=40$ -----> equation A

Marc is half as old as Tony

so

$x=\frac{y}{2}$

$y=2x$ ----> equation B

Marc is three times as old as Ben

so

$x=3z$

$z=\frac{x}{3}$ ----> equation C

substitute equation B and equation C in equation A

$x+2x+\frac{x}{3}=40$

solve for x

$\frac{10x}{3}=40$

$x=40(3)/10\\x=12\ years$

therefore

Marc's age is 12