Amovie collector has 105 movie posters and 90 band posters if she sells 21 movie posters then how many band posters should she sell to maintain the same ratio

Hi there! :)

In order to maintain the same ratio, she should sell 18 band posters.

Step-by-step explanation:

Initial ratio:

Ratio is: 105 movie posters for 90 band posters = 105 : 90

She sells 21 movie posters, which means that we are left with 105 movies minus the 21 she sold.

105 - 21 = 84 → She now has 84 movie posters.

In order to answer your question, you'll need to use the cross product method:

105 movie posters → 90 band posters

84 movie posters  → X

(90 × 84) ÷ 105 = X

7,560 ÷ 105 = X

72 = X ⇒ Number of band posters she should have left to maintain the same ratio.

She has 90 band posters :

90 - X = 72

Add "X" to each side of the equation → 72 + X = 72 + X

90 = 72 + X

Subtract 72 from each side of the equation → 90 - 72 = 18

18 = X

There you go! I really hope this helped, if there's anything just let me know! :)

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step-by-step explanation: