A jar contains black and white marbles in the ratio 2:5. If the jar contains total of 35 marbles, how many of the marbles are black?

10 black marbles

Step-by-step explanation:

Let black marbles be=2x

Then white marbles=5x

Total marbles=7x which in turn is equal to 35. Hence x=5

Black marbles=2*5=10

H2H

It's a direct variation condition,

hence ratio remains constant.

39 - 3

x - 4

x = 4×39/3 = 4×13 = 52 .. (for first blank space)

39 - 3

x - 10

x = 39×10/3 = 13×10 = 130 .. (for second blank space)