human
Dorothy, Julia, and Robert go to the store to buy school supplies. Dorothy buys half as many pens as Julia. Julia buys three times as many pens as Robert. Robert buys 4 pens. If one pen costs $1.50, how much money did the three friends spend in total on pens?
assistant
How many pens does Julia buy? ** Julia buys 4 * 3 = <<4*3=12>>12 pens
How many pens does Dorothy buy? ** Dorothy buys 12/2 = <<12/2=6>>6 pens
How many pens did the three friends purchase in total? ** The total number of pens purchased is 4 + 12 + 6 = <<4+12+6=22>>22 pens
How much money did the three friends spend in total on pens? ** The total cost of the pens is 22 * $1.50 = $<<22*1.5=33>>33
#### 33