What is the difference of the cube and square of the common root of $(x^{2}-8x+15)=0$ and $(y^{2}+2y-35)=0$

correct answer was 100

root of $x^2-8x+15=0$ is $[3,5]$

root of $y^2+2^y-35=0$ is $[-7,5]$

here common root is $5$

now, $5^3-5^2=100$