Explanation:
look at the green point.
what is the closest whole number to the green point ?
to me it is very clearly 35.
you understand what a whole number is ?
it is a number without any fractional part.
so, like 1, 2, 3 ...
and not like 1.5, 0.33, 17.892 ...
and the nearest ten (number)?
what that means is something like 10, 20, 30, ...
so, clearly, from the position of A, it is closer to 40 than to 30 (as it is right of the middle 35).
therefore, A rounded to the nearest ten is 40.