The first 10 floors are 10*12=<<10*12=120>>120 feet
There are a remaining 20-10=<<20-10=10>>10 stories
They are each 12+3=<<12+3=15>>15 feet
So those stories are 15*10=<<15*10=150>>150 feet
So the total height is 120+150=<<120+150=270>>270 feet
#### 270