When a hole is dug for one tree, 3 kg of mulch and 45 kg of fertiliser must be placed in the hole before the tree is planted. Another 0.5 kg of mulch must be spread around the tree. a. How much fertiliser and how much mulch must be bought for b. If another 13 trees are added to the number of trees to be planted, how much extra fertiliser and mulch must be bough c. Is this an example of direct or inverse proportion? 120 trees?