In the month of november a dance troupe had 150 members. in december there was a 20% decrease in the members. in january there was a 20% increase from the month before. how many members were in january?

Hello!
When I do something with percentages I always look at it as if it was a fraction. When there is a decrease of 20%, it means that you keep 80 percent of the 100 percent, so 80/100. To calculate this, we devide 150 by 100 (1.5) and then multiply by 80 (120)

We do the same thing for January, only this is an increase, so 120 percent. the fraction is 120/100. 120 (where we left off) divided by 100 (1.2) times 120 is 144 members, this is your answer!

Hope this helped you!