In this line of circles
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the ratio of red circles to blue circles is 1 :3
How many more red circles would
need to be added to make the ratio of red to blue 3 : 1?

The ratio 1: 3 means there is 1 red one and 3 blue ones.

For the ratio 3:1 there needs to be 3 red for every one blue.

You have 3 blue ones, so you would need 3 x 3 = 9 red ones.

You already have 1 red one so you would need 8 more.

$54.99

step-by-step explanation:

$54.99 includes 500 min. if she does not exceed 500 min then her bill is $54.99