Marla has to spend 20 minutes driving one way to her son's school, then 70 minutes attending parent-teacher night, then the same amount of time driving home. How many minutes does Marla spend on this errand in total? Let's answer step by step:
First multiply Marla's one - way driving time by 2 to find her total driving time: 20 minutes * 2 = 40 minutes. Then add Marla's driving time to the time spent attending the conference to find the total time: 70 minutes + 40 minutes = 110 minutes. The answer: 110.