{loadmoduleid 241}
problem:
A car is going at at speed of 60 mph. It takes 12 minutes to the city.
How long does it take the same car if it is going at a speed of 80 mph?
{loadmoduleid 234}
answer:
1. step: proportion
* 60 mph – 12 minutes
: 80 mph – x minutes
2. step: which proportion?
↑more speed ↓less minutes = inverse proportion
3. step: formula
x = 12 * 60
80
x = 9 minutes
4. step: answer
It takes the car 9 minutes to the city.