so if he is running 26.2 miles (I just turned the fraction into a decimal) then you should find out 1/4 AKA 25%. So, 10% of 26.2 would be 2.62. 1% would be 0.262. So 2.62 times 2 (because 20% is 10% times 2) so it is 5.24. 0.262 times 5 is 1.31. You could also take half of the 10% decimal to get 5%. Add 1.31 and 5.24 to get 6.55. So 25% of 26.2 is 6.55. BUT WAIT! You want 3/4 of this number. So you multiple 6.55 by 3 to get 19.65. So the answer is 19.65 miles in the marathon after 3/4 of the way.