human
Building one birdhouse requires 7 planks and 20 nails. If 1 nail costs $0.05, and one plank costs $3, what is the cost, in dollars, to build 4 birdhouses?
assistant
How much do the planks cost? ** The cost of the planks for one birdhouse is 7 * 3 = $<<7*3=21>>21.
How much do the nails cost? ** And the nails are a cost of 20 * 0.05 = $<<20*0.05=1>>1 for each birdhouse.
How much does it cost to build one birdhouse? ** So to build one birdhouse one will need 21 + 1 = $<<21+1=22>>22.
How much does it cost to build 4 birdhouses? ** So the cost of building 4 birdhouses is at 4 * 22 = $<<4*22=88>>88.
#### 88