- What's on the desk? ( )
- _________
A:Yellow.
B:Twelve crayons.
C:It's Wednesday.
如果关于x、y的单项式2axcy与单项式3bx3y是同类项,并且2axcy+3bx3y=0(xy≠0),当m的倒数是﹣1,n的相反数是12时,求(2a+3b)99+mc﹣nc的值.