topkids

07-20-2011, 10:02 PM

please help! A proffessor is three times as old as one of his pupil. four years ago he was four times as old as freddie was at that time? how old is freddie?

View Full Version : Split-Linear Algebra!

topkids

07-20-2011, 10:02 PM

please help! A proffessor is three times as old as one of his pupil. four years ago he was four times as old as freddie was at that time? how old is freddie?

soroban

07-21-2011, 06:57 PM

Hello, topkids!

A professor is three times as old as Freddie.

Four years ago, he was four times as old as Freddie at that time.

How old is Freddie?

\text{Let }x\text{ = Freddie's age now.}

\text{Then }3x\text{ = prof's age now.}

\begin{array}{c}\text{Four years ago, they were both 4 years younger.}\\ \text{Freddie's age was }x-4 \\ \text{The prof's age was }3x-4 \end{array}

\text{At that time: }\:\underbrace{\text{prof's age}}_{3x-4} \; \underbrace{\text{was}}_{=} \; \underbrace{\text{4 times}}_{4\;\times} \; \underbrace{\text{Freddie's age}}_{x-4}

\text{There is our equation! }\quad 3x-4 \:=\:4(x-4)

A professor is three times as old as Freddie.

Four years ago, he was four times as old as Freddie at that time.

How old is Freddie?

\text{Let }x\text{ = Freddie's age now.}

\text{Then }3x\text{ = prof's age now.}

\begin{array}{c}\text{Four years ago, they were both 4 years younger.}\\ \text{Freddie's age was }x-4 \\ \text{The prof's age was }3x-4 \end{array}

\text{At that time: }\:\underbrace{\text{prof's age}}_{3x-4} \; \underbrace{\text{was}}_{=} \; \underbrace{\text{4 times}}_{4\;\times} \; \underbrace{\text{Freddie's age}}_{x-4}

\text{There is our equation! }\quad 3x-4 \:=\:4(x-4)

Powered by vBulletin® Version 4.2.2 Copyright © 2014 vBulletin Solutions, Inc. All rights reserved.