Jar contains 20 white marbles, 30 black marbles and some red marbles. Half of the marbles are black. What is the ratio of white to red marbles - how many marbles are in the the jar? - how can you find thee number of the red marbles?

Answer:the ratio of white to red marbles is 2:1

The number of marbles in the jar is 60.

The number of red marbles is 10

Step-by-step explanation:

Let x represent the total number of marbles in the bar.

The jar contains 20 white marbles, 30 black marbles and some red marbles.

Let r represent the number of red marbles. Therefore,

20 + 30 + r = x

Half of the marbles are black. This means that

x/2 = 30

x = 2 * 30 = 60

Therefore,

20 + 30 + r = 60

50 + r = 60

r = 60 - 50 = 10

The ratio of white to red marbles would be

20/10 = 2:1