Well first we have to add 7/12 and 3/4 together which is 7/12+3/4=4/3. Now we have to reduce that to simplest form. Which would be 1 1/3 is 7/12+3/4 in simplest form!
Try dividing the surface area of the wall by 6.
The problem gives you the time in hours, but you're looking for your answer in minutes so change 1/10 of an hour to minutes first. To do this, multiply 1/10 by 60 to get 6 minutes. Since there are 4 quarters in a whole, multiply 6*4. It would take her 24 minutes to drink the whole shake