若x和y互为相反数,则3x-10+3y+y/5x=

问题描述:

若x和y互为相反数,则3x-10+3y+y/5x=

x+y=0
x=-y
x/y=y/x=-1
3x-10+3y+y/5x
=3(x+y)-10+y/5x
=0-10-1/5
=-10.2