help please

from first equation    9-x  = y      sub into 2nd equation

x(9-x) =10

-x^2+9x-10 = 0      quadratic formula shows x = 9/2 +- sqrt41 /2          if x =      1.29844     or   7.70156

                                                                                                                 y =       7.70156    or   1.29844

then    x^3  + y^3  =   459

$x^3 + y^3 = (x + y)(x^2 - xy + y^2) = (\color{blue}x + y\color{black})((\color{blue}x + y\color{black})^2\, - \,3\color{red}xy\color{black})$

Now you can substitute the values.