Answer:
9 boxes
Explanation:
Boxes of Cereal 3 for the price of 2, the the price of the 3 boxes of cereals must be : 2 × £2.89 = £5.78
Boxes Megan can buy for the offer = £20 ÷ £5.78 = 3.46 (to 3 s.f.)≈ 3
3 × 3 =9 packs
But they actually only cost : 3 × £5.78 = £17.34
Therefore after buying the offer Megan has £20 - £17.34 = £ 2.66 left, which is not enough to buy a single pack, so the answer is 9.