Answer: 60 days
Step-by-step explanation:
To get the number of days that both of them will be washing the cars on thesame day, we have to find the lowest common multiple of 15 and 20. This will be:
Multiple of 15 = 15, 30, 45, 60, 75, 90
Multiples of 20 = 20, 40, 60, 80, 100
Lowest common multiple = 60
Therefore, they'll be Washing the car on thesame day on the 60th day.
