(1)计算:(5x)/(3y)*(-9y)/(10x^2)
=(5x)(-9y)/(3y)(10x^2)
= -3/2x
(2)化简：(x+1)/(x)÷(1)/(x^2-x)
=(x+1)/(x)÷(1)/(x)(x-1)
=(x^2-1)/(x)(x-1)÷(1)/(x)(x-1)
=x^2-1
(3)计算：(1+m)/(1-m)*(m^2-1)
=(1+m)/(1-m)*(m+1)(m-1)
= -(1+m)(m+1)
= -(m+1)^2
(4)化简：x^2/y-x-y^2/y-x
=(x^2-y^2)/(y-x)
=(x+y)(x-y)/(y-x)
= -x-y
(5)计算：(2-x)/(x^2-4)+(x+3)/(2+x)
=(2-x)/(x+2)(x-2)+(x+3)/(2+x)
= -1/(x+2)+(x+3)/(2+x)
= (-1+x+3)/(x+2)
= 1