Mike, an experienced bricklayer, can build a wall in 2 hours, while his son, who is learning, can do the job in 4 hours. How long does it take for them to build a wall together.

You coordinate volunteers for litter cleanup in local parks. your spreadsheet lists drivers and the number of seat belts in each driver’s car. the spreadsheet calculates the number of drivers (d) and the total number of seat belts (s). you want to know the maximum number of volunteers, besides drivers, that can be transported to the park in a single trip given that each person must have a seat belt of their own.