Under 60 minutes the teacher spoke 1/6 of the time and the students worked 1/4 of the time. Rest of the time they work together. How long do they work together?
1/6 of 60 = 10 minutes
1/4 of 60 = 15 minutes
So
10 + 15 = 25 minutes
And
60 - 25 = 35 minutes that they worked together