The smallest positive integer when multiplied by 392, the product is a perfect square, is 

[(169×121)÷(11×13)]-3=?

Direction: what should come in place at question mark(?).

$$ {1\over 8}×(223+?)=71$$

Solve the following equation 24 + 4 ÷ 4

If 2x + 3y - 5z = 18 , 3x + 2y + z = 29 and x + y + 3z = 17 , then what is the value of xy + yz + zx ? 

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

80% of 10% of 340 = ?

The sum of the squares of two positive integers is 100 and the difference of their squares is 28. The sum of the numbers is: 

Simplify : $$ {9\over 13} ÷{18\over 26}÷{90\over 52}$$