# Linear Systems

• Dec 5th 2007, 04:08 PM
Linear Systems
:confused:hey,
i dont understand this question. I tried solve it but i got lost in the middle somewhere. Could you please help me with it, please?

Kareem took 5 hours to drive 470km from Sudbury to Brantford. For part of the trip, he drove at 100km/h. For the rest of the trip he drove at 90km/h. How far did he drive at each speed?
• Dec 5th 2007, 04:53 PM
Soroban

Quote:

Kareem took 5 hours to drive 470km from Sudbury to Brantford.
For part of the trip, he drove at 100km/h. For the rest of the trip he drove at 90km/h.
How far did he drive at each speed?

Let $t$ = times he drove at 100 km/hr.
Then $5-t$ = time he drove at 90 km/hr.

He drove $t$ hours at 100 klm/hr.
. . His distance was: . $100t$ km.

He drove $5-t$ hours at 90 km/hr.
. . His distance was: . $90(5-t)$ km.

His total distance was 470 km.

There is our equation! . . . $100t + 90(5-t) \:=\:470$

Can you finish it now?

• Dec 6th 2007, 01:04 PM