Final answer:
Noah will spend £26.91 on coffee sachets.
Step-by-step explanation:
To find out how much Noah spends on coffee sachets, we need to calculate the total number of sachets he uses in four weeks and multiply that by the cost of one sachet pack.
In one day, Noah uses 3 sachets. In four weeks, there are 7 days in a week, so in total there are 4 × 7 = 28 days.
This means Noah uses a total of 3 × 28 = 84 sachets in four weeks.
Since there are 10 sachets in a pack, Noah needs to buy 84 ÷ 10 = 8.4 packs of sachets.
Since he cannot buy fractional packs, Noah needs to buy 9 packs in total.
The cost of one pack is £2.99, so Noah will spend 9 × £2.99 = £26.91 on coffee sachets.