Question

1. Kim's age is twice that of her sister. When you add Kim's age to her sister's age, you get 36. 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.

Answer 1

Kim's age is twice of that of her sister. We'll let k2 = Kim and k = Kim's sister.
So, k2. When you add Kim's age to her sister age you get 36.
Because Kim is twice the age of her sister k2. And because it said 'add' then we put a + sign. k2 + s = 36. Now let's solve it. 

k2 + k = 36 < Given
3k = 36 < Combine like terms
k = 12 < Divide both sides by 3

We know Kim's sister is 12 y/o but what about Kim herself? Earlier we assigned Kim to k2. Substitute 12 for k and you get 12(2) = 24

Kim's sister is 12 y/o and Kim is 24 y/o