Double Age

Bob is 30 years old, and twice as old as Andy. so if Bob is x years old Andy is $\frac{x}{2}$ years old.

Bob is 30. so Andy is $\frac{30}{2}$ =15 years old.

now, difference between Bob & Andy's age is = $30-15=15$ years old

so, if Bob is 60 ,Andy will be = $60-15=45$ years old

When Bob is $30$ years old, Andy is $15$ .

It takes $30$ years for Bob to become age $60$ . By then, Andy will be $15+30 = 45$ years old.

People who aren't paying attention may choose 30, accidentally thinking that age is a ratio relationship. It's not possible for 30 years to go by for one person but only 15 years for someone else.

$\frac{30}{2}$ = 15, 60 - 15 = 45

If Bob is 30 yrs and is twice as old as andy then Andy = $15 yrs$

How much time will it take for Bob to be 60 years?

$60-30=30$ So 30 years.

While Andy in 30 yrs time will be:

$15+30=45$

So his age will be 45 yrs.