Word Problem: Work Order

Amanda's son was born on Amanda's 25th birthday. If in five years Amanda's age will be triple her son's age, how old is her son now?

Correct! Let $$x$$ be the age of her son now. Amanda's age is $$x + 25$$. In five years her son's age will be $$x + 5$$ and her age will be $$x + 25 + 5$$. In five years, her age equals three times the age of her son. This translates into the equation: >$$x + 30 = 3(x + 5)$$. Note that (seven years and six months) = 7.5 years. You can plug 7.5 into this equation to get: >$$7.5 + 30 = 3 (7.5 + 5)$$ >$$37.5 = 3(12.5)$$. Alternatively, you can solve the equation: >$$\displaystyle x + 30 = 3(x + 5)$$ >$$\displaystyle x + 30 = 3x + 15$$ >$$\displaystyle 15 = 2x$$ >$$\displaystyle 7.5 = x$$.

Incorrect. Let $$x$$ be the age of her son now. Find the age of the mother now. Then find both ages in five years. Set up the equation (mother's age in five years) = (son's age in five years). Note that six years and four months = $$6 \frac{1}{3}$$ years. Plugging $$\frac{19}{3}$$ into the equation does not work.

Incorrect. Let $$x$$ be the age of her son now. Find the age of the mother now. Then find both ages in five years. Set up the equation (mother's age in five years) = (son's age in five years). Note that six years and nine months = $$6 \frac{3}{4}$$ years. Plugging $$\frac{27}{4}$$ into the equation does not work.

Incorrect. Let $$x$$ be the age of her son now. Find the age of the mother now. Then find both ages in five years. Set up the equation (mother's age in five years) = (son's age in five years). Note that seven years and three months = $$7 \frac{1}{4}$$ years. Plugging $$\frac{29}{4}$$ into the equation does not work.

Incorrect. Let $$x$$ be the age of her son now. Find the age of the mother now. Then find both ages in five years. Set up the equation (mother's age in five years) = (son's age in five years). Plugging 8 into the equation does not work.

Six years and four months

Six years and nine months

Seven years and three months

Seven years and six months

Eight years