Alan is 5 years older than Bob. Bob is twice as old as Cindy. All their ages add up to 20. What are their ages?

1 answer:

6 0

We can use a variable equation to solve this. Let A represent alan's age, B represent bob's age, and C represent Cindy's age. So Bob's age would be Alan's age - 5, or a -5 = B. Then Bob's age would be double Cindy's age, so that means 2 multiplied by Cindy's age = Bob's age, or 2C = B. Your two equations are:

A - 5 = B
2C = B

Also a third equation that helps is A + B + C = 20.

Finally, here are the ages.
Alan = 11 years old
Bob = 6 years old
Cindy = 3 years old.

PS: Sorry, I'm not that good at explaining things, but here are the answers

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A lighthouse operator sights a sailboat at an angle of depression of 12 degrees. If the sailboat is 80m away, how tall is the li

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Check out the attached image for the drawing of how this would look. The drawing isn't 100% needed but it helps I think.

Based on the figure shown in the attachment, we have a right triangle with the adjacent leg of 80 (this leg is closest to the bottom 12 degree angle) and an opposite leg of h

In short,
adjacent = 80
opposite = h

We'll use the tangent rule
tan(angle) = opposite/adjacent
tan(12) = h/80
80*tan(12) = h
h = 80*tan(12)
h = 17.0045249336018 <<-- see note below

So the lighthouse is roughly 17.0045249336018 meters tall

Answer: 17.0045249336018

Note: Make sure you are in degree mode. The value is approximate. Round this answer however you need to