Question 267120
Bob gave 4/5 of his pencils to Barb, then gave 2/3 of the remaining pencils to Bonnie. Bob ended up with 10 pencils left, how many did he start with?

work backwards-->
10 pencils left is the 1/3 Bob did not give to Bonnie,
that makes 30 pencils before he gave 20 to Bonnie

the 30 pencils is the 1/5 Bob did not give to Barb,
that makes 150 pencils (30*5=150) Bob had to begin with

now work forward to check --> 150 pencils
                         less 120 to Barb --> (this is 4/5, 4/5 * 150 = 120)
                          now  30 pencils -->
                         less  20 to Bonnie --> (this is 2/3, 2/3 * 30 = 20)
                        left with 10 pencils