how to calculate power in band

Dear all:
I need to calculate total band power, the spec as below,
total number of :15 carrier
each carrier power : -10dBm
channel spacing=40Mhz

can anybody help me to calculate?

Thanks.

10log15 + (-10dBm) = 1.76dBm

Thanks noise,
1. so the channel spacing or symbol rate don't have any relationship with caliculate total power ?
2. if each carrier have different power level, how to calculate ?

I don't understand

jayce3390,
you means you don't understand my questions ?