15% of the students in Mr. Rennard's classes watch the local news every night. Mr. Rennard found that 136 of his students do not watch the local news. How many total students are in Mr. Rennard's classes?

What we are saying here is 136 students represent the rest of the students which is 100% minus 15% or 136 represents 85%. All we need to do (there are several ways but I prefer this one) divide 136 by 85 then multiply by 100 to find answer which is 160

160 students.