1) what you would have to do in order to solve this problem is divide 3 3/4 by 10 and the answer is to that will be how much mix is needed in order to make one cup of drink.
work
3 3/4 / 10
answer
375/1000
2) 3 3/4= 10
11 1/4=x
to solve for x (which is the unknown variable) you would have to cross multiply which is doing 11 1/4 multiply 10 which equals 112 1/2 now take this number and divide it by 3 3/4 which gives you an answer of 30 cups with 11 1/4 scoops of drink mix
Answer-
30 cups