Answer
$(5x-7y)(3x-2y)$
Work Step by Step
$15x^{2}+11xy-14y^{2}$
... ... Searching for two factors of $ac=-210$ whose sum is $b=+11,$
we find$\qquad 21$ and $-10.$
Rewrite the middle term and factor in pairs:
$=15x^{2}+21xy-10xy-14y^{2}=$
$=3x(5x-7y)-2y(5x-7y)$
= $(5x-7y)(3x-2y)$