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