If a + b = 10 and $\frac{3}{7}$ of ab = 9, then the value of $a^3 + b^3$ is :

350 270 370 360

370

If x + y  = n then, $x^3 + y^3$ = n3 - 3 × n × xy If a + b = 10 $\frac{3}{7}$ of ab = 9, so, by solving ab = 21 then the value of $a^3 + b^3$ = 103 - 3 × 10 × 21 = $a^3 + b^3$ = 1000 - 630 = 370