Answer: 25%
Step-by-step explanation: So first make the number of people who ran the marathon and the number of people who finished the marathon into a ratio
1200:4800
then make that into a fraction, 1200/4800
then make the percent of people who reached the marathon into a fraction, using 100 as the denominator and a variable as the numerator.
for example. p/100 (p, represents the percent)
then cross multiply.
1200x100=1200000
Last divide 1200000 by 4800 to get 25%.