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?

The number of white marbles 'x' is 39

Step-by-step 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

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