28 miles
increasing by 40% = original + increase = 100 + 40 = 140% = 1.4
multiplying 20 by 1.4 gives total he will run
miles run = 1.4 × 20 = 28
Answer:
28 miles
Step-by-step explanation:
Just multiply (20 miles per week) by 1.40: 1.40(20 mpw) = 28 miles
