<human>:  Marcel goes to the store with Dale to buy groceries for cooking dinner. Marcel buys 10 ears of corn, and Dale buys half that amount. Dale buys 8 potatoes and Marcel buys some, too. If they check out together and end up buying 27 vegetables, how many potatoes did Marcel buy?
<bot>: How many ears of corn did Dale buy? ** Marcel bought 10 ears of corn and Dale bought 1/2 what Marcel did, 10 x 1/2 = 10/2 = <<10*1/2=5>>5 ears of corn that Dale bought.
How many vegetables did Marcel and Dale buy? ** Together, Marcel and Dale bought 10 + 5 = <<10+5=15>>15 ears of corn, or 15 vegetables.
How many vegetables did Marcel and Dale buy? ** They end up buying 27 vegetables total, and from those 27, 15 of them were corn.
How many potatoes did Marcel and Dale buy? ** The rest of the vegetables are potatoes, 27 vegetables - 15 ears of corn = <<27-15=12>>12 potatoes.
How many potatoes did Marcel buy? ** Dale bought 8 potatoes, so Marcel bought 12 - 8 = <<12-8=4>>4 potatoes.
#### 4