Question

A is 15 year older than B now.Ten year ago,A was four times B's age .What are the age of B.

Answer 1

Let the age of B is x at present
so A present age is x+15
10 yrs ago their age was x-10 and x+15-10=x+5 respectively
by question x+5=4*(x-10 )
or x=15
age of B is 15 yrs

Answer 2

$\mathfrak{Step-By-Step\:Explanation:}$

Let the age of B be x years.

So A's age = (x+15) years.

10 years ago,

• A's age = (x+15-10) = (x+5) years.
• B's age = (x-10) years.

According to question ,

$\implies\bold{(x-10)4=(x+5)}\\\\\\\implies\bold{4x-40=x+5}\\\\\\\implies\bold{4x-x=40+5}\\\\\\\implies\bold{3x=45}\\\\\\\implies\bold{x=\dfrac{45}{3}}\\\\\\\implies\bold{x=15.}\\\\\\\boxed{\boxed{\bold{A's\:age=30\:years\:\&\:B's\:age=15\:years}}}$