3/8 of a box of balls are red, 3/10 of them are green and the rest are black. If there are 36 green balls, how many black balls are there?
Green ball in the box 3/10 part =36 numbers. 1unit = 120 numbers.
Red balls =3/8×120=24 numbers
Black balls=Total number of balls - red balls+ green balls= 120- 36+24=60 numbers.
+129 Let total no. of balls be x
==> (3/10)*x = 36
==> x = 120
No. of black balls = x-(3/8x+3/10x) = 13x/40 = (13/40)*120 = 39 balls
