the trees must be planted, only seven people show up to work. How many trees must each person plant? When a hole is dug for one tree, 3 kg of mulch and \( 4,5 \mathrm{~kg} \) of fertiliser must be placed in the hole before the tree is planted. Another \( 0,5 \mathrm{~kg} \) of mulch must be spread around the tree. a. How much fertiliser and how much mulch must be bought for 120 trees? b. If another 15 trees are added to the number of trees to be planted, how much extra fertiliser and mulch must be bought? c. Is this an example of direct or inverse proportion?

Each person will need to plant \( \frac{120}{7} \approx 17.14 \) trees, so about 17 trees each, with a few extra trees for the last person! When it comes to fertiliser and mulch, for 120 trees, you'll need 540 kg of fertiliser (at 4.5 kg per tree) and 360 kg of mulch (3 kg per tree and 0.5 kg around each tree). If you add 15 more trees, that totals 135 trees. The extra requirements would be 67.5 kg of fertiliser (4.5 kg per tree) and 45 kg of mulch (3 kg plus 0.5 kg per tree) for those additional trees. This scenario illustrates direct proportion because as the number of trees increases, the amount of fertiliser and mulch needed increases in a consistent ratio.