problem:
Jane fills apple juice into thirty 0,75-l bottles.
If she uses 0,5-l bottles, how man bottles can she fill with the same amount of apple juice?
answer:
1. step: proportion
* 0,75 l – 30 bottles
: 0,5 l – x bottles
2. step: which proportion?
↓less volume ↑more bottles = inverse proportion
3. step: formula
x = 30 * 0,75
0,5
x = 45 bottles
4. step: answer
45 bottles are needed.