Q. 205.0( 6 Votes )

A bag contains wh

Answer :

Let the no of white balls = x


Let the no of red balls = y


No of black balls = 20 [given]


Total No of balls = x + y + 20




⇒ 10x = 3(x + y + 20)

⇒10x = 3x + 3y + 60

⇒7x - 3y = 60 ….[1]


⇒ 20(5) = 2(x + y + 20)
⇒ 100 = 2x + 2y + 40
⇒2y + 2x = 60

⇒x + y = 30

⇒x = 30 - y ….[2]

Put the value of x in (1) to get,

⇒7(30 - y) - 3y = 60

⇒210 - 7y - 3y = 60

⇒ 210 - 60 = 10y

⇒10y = 150

⇒ y = 15

No of red balls = 15

using this in eqn 2

x = 30 - 15
= 15

No of white balls = 15

Total no of balls : x + y + 20
= 15 + 15 + 20
= 50


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