There are 8 red pens in Maria's desk drawer. There are 10 more black pens than red pens. There are also 7 more blue pens than red pens. How many pens are there in all?
Maria has 8 + 10 = <<8+10=18>>18 black pens.
Maria has 8 + 7 = <<8+7=15>>15 blue pens.
Maria has 8 + 18 + 15 = <<8+18+15=41>>41 pens in total.
#### 41