Question

A grandfather is fifteen times older than his grandson. He is also 56 years older than him. Find their present years.​

Answer 1

Answer:

Let the present age of grandson be a.

So the age of grandfather should be 15 times of a that's 15a.

Also, grandfather is 56 year older than his grandson.

So,

→ age of grandfather = age of grandson + 56

→ 15a = a + 56

→ 15a - a = 56

→ 14a = 56

→ a = 56 / 14

→ a = 4

Hence the present age of grandson is 4 year and that of grandfather is 15*4 = 60 year

Answer 2

Answer:

Grandpa: 60 yrs old

Grandson: 4 years old

Step-by-step explanation:

This is linear systems. Set up 2 equations. We know that the grandfather is 15 times older than the grandson, and is 56 years older.

Let y represent the grandfather's age.

Let x represent the grandson's age.

1. y = 15x (the grandpa is 15 times older than the kid)

2. x= y - 56 (the grandson is 56 years younger than the grandpa

Sub 2 into 1:

y= 15 (y-56)

y= 15y - 840

Isolate for y (the grandpa's age)

-14y= -840

y = 60

Since y = 60, we can plug this value into equation #2.

x = 60 - 56

x = 4

Therefore, the grandpa is 60 years old and the grandson is 4 years old. QED