Question

Sam is one-third as old as his brother. In six years Sam will be one-half as old. How old is Sam now?

Answer 1

S = Present Sam's age

B = Present brother's age


Sam is one-third as old as his brother mean:

S = B / 3


After six year Sam will be S + 6 years od.

Brother will be B + 6 years old.


In six years Sam will be one-half as old mean:

( S + 6 ) / ( B + 6 ) = 1 / 2

Now you must solve system of 2 equations with 2 unknows:

S = B / 3

( S + 6 ) / ( B + 6 ) = 1 / 2

Try solve this.


The solutions are :

S = 6 years old

B = 18 years old

Proof:

S = B / 3 = ( 1 / 3 ) B

S / B = 6 / 18 = 6 / ( 6 * 3 ) = 1 / 3


( S + 6 ) / ( B + 6 ) = ( 6 + 6 ) / ( 18 + 6 ) = 12 / 24 = 12 / ( 12 * 2 ) = 1 / 2

Answer 2

Pat had 5 snowballs less than Sam