Matt spends 80 minutes washing the outside of his car and 1/4 that amount of time cleaning the inside. How long does he spend cleaning his car total?
Work out the solution step by step. 
First find the time Matt spends cleaning the inside of his car: 80 minutes / 4 = 20 minutes
Then add that time to the time he spends cleaning the outside to find his total cleaning time: 20 minutes + 80 minutes = 100 minutes