Last week’s answer: 21 squared. This is a fact that you simply have to either memorise or calculate during the exam, as questions like this can come up. It also requires knowledge of the term ‘more than’, as the answer 20 squared (= 400) is incorrect.
This week’s problem: What is the product of the sum of 4 and 3, and the difference between 7 and 2?
The answer will be in next week’s weekly problem.