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
