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 :
![(17y)/(3)+y = 120\\\\(20y)/(3)=120\\\\y = 18\\\\x = 120 - 18\\\\x = 102](https://img.qammunity.org/2021/formulas/mathematics/college/sxps0rg5b2glzatcckuytswu5ktad49p6b.png)
Therefore, the number of red and black marbles are 102 and 18 respectively.