Kim's age is twice that of her sister. when you add kim's age to her sister's age, you get 60. how old is each sister? (a) write an equation that represents the situation. explain any variable used. (b) solve the equation from part (a). show your work. state your solution as a complete sentence.

Let Kim = k, and her sister = s

k = 2s

k + s = 60

First, plug in 2s for k in the equation "k + s = 60"

2s + s = 60

Simplify

(2s + s) = 60

3s = 60

Isolate the s. Note the equal sign. What you do to one side, you do to the other. Divide 3 from both sides

3s/3 = 60/3

s = 60/3

s = 20

Her sister is 20 years of age.

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