Question

When a question asks you to "Explain", what are you expected to do
AND

Answer 1

They are asking you "how" you managed to get your answer

Explanation:

say the question is 5×5=25 and the question say Explain;"well if you add 5+5+5+5+5 is equals 25"

Answer 2

they want to tell you why the answer is what it is

Explanation: