Which explanation best describes how to solve this problem?
on tuesday, lara spent 40 minutes running. she rode her scooter for 25 minutes and then read a magazine for 10 minutes. lara then fixed herself a snack. she started fixing herself a snack at 4: 30.
what time did lara start her run?
a.
substitute simpler numbers. add 4 + 2 + 1. subtract 7 minutes from 4: 30. lara started her run at 4: 23.
b.
work backward. start at 4: 30, subtract 10 minutes, therefore started reading at 4: 20. subtract 25 minutes, therefore started riding scooter at 3: 55. subtract 40 minutes, therefore started running at 3: 15. lara started her run at 3: 15.
c.
draw a diagram. draw a clock. first show the minute hand starting at 12. draw another clock. add 40 minutes. the minute hand now points to the 8. draw another clock. add 25 minutes. the minute hand now points to the 1. draw another clock. add 10 minutes. the minute hand now points to the 3. lara started running at 15 minutes past the hour.
d.
guess and test. start at 1: 00, add 40 minutes. the time is now 1: 40. add 25 minutes. the time is now 2: 05. add 10 minutes. the time is now 2: 15. lara started running at 2: 15.