Let us check which term can be simplified further:
#x^2-y^2# = #(x+y)(x-y)#
Then we know: #1/(a/b)# = #1xxb/a#
so now we simplify the original expression:
#((10ab)/(x^2-y^2))/((5a(x-y))/(3ax(x+y)))# = #(10ab)/((x+y)(x-y))xx(3ax(x+y))/(5a(x-y))#
#((10ab)/(x^2-y^2))/((5a(x-y))/(3ax(x+y)))# = #(10ab)/(cancel((x+y))(x-y))xx(3axcancel((x+y)))/(5a(x-y))#
#((10ab)/(x^2-y^2))/((5a(x-y))/(3ax(x+y)))# = #(10ab)/((x-y))xx(3ax)/(5a(x-y)#
#((10ab)/(x^2-y^2))/((5a(x-y))/(3ax(x+y)))# = #(30a^2bx)/((5a)(x-y)^2)#
#((10ab)/(x^2-y^2))/((5a(x-y))/(3ax(x+y)))# = #(30/5)xx((a^(2-1)xxbx))/(x-y)^2#
#((10ab)/(x^2-y^2))/((5a(x-y))/(3ax(x+y)))# = #(6abx)/(x-y)^2#