Question

A bag contains 120 marbles. Some are red and the rest are black. There are 17 red marbles for every 3 black marbles. How many red marbles are in the bag?

Answer 1

Given :

A bag contains 120 marbles. Some are red and the rest are black. There are 17 red marbles for every 3 black marbles.

To Find :

How many red marbles are in the bag.

Solution :

Let, number of red and black marbles are x and y respectively.

So, x + y = 120    ....1)

Now, it is given that there are 17 red marbles for every 3 black marbles.

So, 3x = 17y        ....2)

Putting value of x from equation 2) to equation 1), we get :

$\dfrac{17y}{3}+y = 120\\\\\dfrac{20y}{3}=120\\\\y = 18\\\\x = 120 - 18\\\\x = 102$

Therefore, the number of red and black marbles are 102 and 18 respectively.