if mark uses 3 3/4 tablespoons of coffee to make 10 cups of coffee, how much would he need to make one cup of coffee?

0/3

3 3/4 = 14/4 tbsp   per 10 cups

14/4  /  10  =   14/40  =  7/20 ths of a tablespoon  (about 1/3)

Just divide: 3.75 / 10=.3375 tablespoon of coffee to make 1 cup. Or just over 1/3.