The sum of a number, which I have named 'n', and 7 can be written as the expression:
n+7
remember the word 'is' in a written problem indicates where you'll most likely use an =,≥,≤ sign. Since they say that it is 'no more than' we know that n+7 is less than or equal to the given number, so we use '≤'.
The cross-section of a square pyramid will be a square. The section above the cross-section taken will basically be a similar but smaller square pyramid. D is the correct answer.