If a³ – b³ – c³ – 3abc = 0, then 

115% of 4880 – 85% of 1640 = ?

$$ if \ {1\over x}+x=4,$$ then find $${1\over x^2}+x^2$$

If m + n = 1, then what will be the value of m³ + n³ + 3mn?

Direction: What approximate value will come in place of the question mark (?) in the following question? (You are not expected to calculate the exact value)

? × 350.01 ÷ 3.992² = 983 ÷ 14.001

If $${8+2\sqrt{3} \over 3\sqrt{3}+5}=a\sqrt{3}-b$$, then the value of a+b is equal to:

$$ {4\over 7}×{2{4\over 5}} ÷{2\over 5}=?$$

If 5x + 5 > 2 + 2x and 5x + 3 ≤ 4x + 5; then x can take which of the following values?