Direction : What should come in place of the question (?) in the following question.

√(?) + 15² = 235

0.8% of a number is 31, then find the number.

Direction : What value should come in the place of question mark (?) in the following questions?

$$ 68\sqrt?-826=262 $$

If 999x + 888y = 1332 and 888 x + 999y = 555.then the value of (x + y) is-

What value will come in place of question mark (?) in the questions given below?

(4425÷25) ×(8.5×16) = ?

The average of some natural numbers is 15. If 30 is added to first number and 5 is subtracted from the last number, the average become 17.5. then the numbers of natural numbers is :

Thrice the square of a natural number decreased by four times the number is equal to 50 more than the number. The number is :

A is inversely proportional to square of B whereas directly proportional to C. Value of A was 27 when value of B was 4 and value of C was 6. Find the value of A when value of B will be 3 and value of C will be 8.