To determine how much it will cost Aftab to buy enough concrete slabs to make the patio, you will need to know the size of the patio and how many slabs are needed to cover it. Once you have this information, you can multiply the number of slabs by the cost per slab to find the total cost. For example, if the patio is 10 square meters and requires 20 concrete slabs to cover it, the total cost would be 3.10 * 20 = £62.