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?
First multiply Marla's one-way driving time by 2 to find her total driving time: 20 minutes * 2 = <<20*2=40>>40 minutes
Then add Marla's driving time to the time spent attending the conference to find the total time: 70 minutes + 40 minutes = <<70+40=110>>110 minutes
#### 110