Give the step-by-step reasoning process and then the final answer. Dana has 15 more pencils than Jayden, who has twice as much as Marcus. How many more pencils does Dana have than Marcus, if Jayden has 20 pencils?
Dana has 15 more pencils than Jayden who has 20, so Dana has 20 + 15 = 35 pencils. Jayden has 20 pencils which is twice as much as Marcus's so Marcus has 20 / 2 = 10 pencils. Dana has 35 - 10 = 25 more pencils than Marcus.
The final answer: 25.