in an 7th grade class with 80 people, seven tenths of the students wore shorts, if three sevenths of those students who wore shorts also wore tank tops, how many 7th graders wore shorts and tank tops

Pls! does anybody know a shortcut for answering these types of questions in the future?

Fanny mendelssohn manages all the magazines and paperback books at a local grocery store. she prices many paperbacks to sell at $7.99. the cost to the store is $5.29. what is the markup rate on a paperback book, based on its cost?

15 points! write the slope-intercept form of the equation of the line through the given point with the given slope. use y-y = m(x-x) to solve. through (2,5) slope= undefined