If 3x + 7y=75, 5x- 5y= 25, then the value of (x +y)=?

What will be the total number of pieces if the length of $$ {5}{1\over4}$$  the rib is cut to 3/4 m length?

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

The smallest positive integer n for which 864 x n is a perfect cube, is: 

Find the value of given expression.

3 – (– 6) {– 2 – 9 – 3} ÷ 7{1 + (– 2) (– 1)}

Find the value of x:
2³ × 3⁴ × 1080 ÷ 15 = 6^x