Machine a can sort 840 pieces of mail per hour, and machine b can sort 760 pieces per hour. how long will it take both machines running at the same time to sort 12,800 pieces of mail?
a) 4 hours
b) 6 hours
c) 7 hours
d) 8 hours

Solve the problem by using a venn diagram a group of students were surveyed about their taste in music.they were asked how they like three types of music: rock, country western and jazz.the results are summarized below: no one dislikes all three types of music.six like all three types of music.eleven don’t like country western.sixteen like jazz.three like country western and jazz, but not rock.six don’t like rock.eight like rock and country western.seven don’t like jazz.how many students were surveyed?