Mark constructed a deck that was 30 feet by 40 feet.  It cost $3 per square foot.  He then paid an extra $1 per square foot for sealant.  How much did he pay?
The deck is 30*40=<<30*40=1200>>1200 square feet
He pays 3+1=$<<3+1=4>>4 per square foot
So he paid 1200*4=$<<1200*4=4800>>4800
#### 4800