Sheet # 12/Writing Equations

Name: _____________________ Date_____________

 1) A boy is 7 years older than his sister.

Let x represent the number of years in the boy's age. The sister's age is represented by x - 7. Write equations showing that:

a) The sum of their ages is 21.

b) The boy's age is equal to two times his sister's age.

c) Three times the sister's age equals seven more than the boy's age.

d) The product of 2 and the boy's age equals the product of 4 and the girl's age.

 2) Joan has twice as much money as Cathy does.

Let m represent the number of dollars that Cathy has; then, 2m represents the number of dollars that Joan has.

Write equations showing that:

 a) Together they have $15.

  b) If Joan spends $5, she and Cathy wil have the same amount of money.

 c) If Cathy spends $3, Joan will have five times as much money as does Cathy,