Kit is twice as old as his friend Sam....

​Kit is twice as old as his friend Sam. Sam is 5 years older than Cara. In 5 years, Kit will be three times as old as Cara. How old is Sam?

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ages now
x = Cara's age now  
x + 5 = Sam's age now {Sam is 5 years older than Cara}
2(x + 5) = Kit's age now {Kit is twice as old as Sam}

ages in 5 years
x + 5 = Cara's age in 5 years  {added 5 onto current age}
x + 10 = Sam's age in 5 years {added 5 onto current age}
2x + 15 = Kit's age in 5 years  {added 5 onto current age}

​2x + 15 = 3(x + 5) {in five years, Kit will be three times as old as Cara}
2x + 15 = 3x + 15 {used distributive property}
x = 0  {subtracted 2x and 15 from each side}
x + 5 = 5  {substituted 0, in for x, into x + 5}

ages now
Cara is 0 {apparently, not 1 year old yet!}
Sam is 5
Kit is 10

ages in 5 years
Cara will be 5
Sam will be 10
Kit will be 15

Ask the House
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