Question

A bag contains white marbles and yellow marbles, 54 in total. The number of white marbles is 6 less than 3 times the number of yellow marbles. How many white marbles are there?

Answer 1

let x be white marbles, y be yellow marbles
x+y=54…(1)
x=3y - 6 …(2)

put (2) into (1)
(3y - 6) + y = 54
4y = 60
y=15

put y=15 into (1)

x + 15=54
x=39

so y=15 x=39

Answer 2

The number of white marbles 'x' is 39

Explanation:

Given :

A bag contains white marbles and yellow marbles, 54 in total.

The number of white marbles is 6 less than 3 times the number of yellow marbles.

To Find : Number of White marbles

Solution :

Let number of white marbles be x

Let number of yellow marbles be y

Since we are given that there are 54 marbles in total.

⇒ x + y = 54 ---(A)

We are also given that the number of white marbles is 6 less than 3 times the number of yellow marbles.

⇒ x = 3y - 6 ---(B)

Solving A and B using substitution method

Put value of x from (B) in (A)

⇒3y - 6 + y = 54

⇒4y - 6 = 54

⇒4y = 54+6

⇒4y = 60

⇒y = 60/4

⇒y = 15

Thus , number of yellow marbles 'y' is 15

To find number of white marbles put value of y in (B)

⇒ x = 3*(15) - 6

⇒x = 45 - 6

⇒x = 39

Thus , The number of white marbles 'x' is 39