Answer:
15 days
Step-by-step explanation:
Given
[tex]Truck\ 1: 3\ days[/tex]
[tex]Truck\ 2: 5\ days[/tex]
Required
Next time they both visit
First, list out days of visitation of each truck
[tex]Truck\ 1: 3, 6, 9, 12, 15, 18, 21\ days.....[/tex]
[tex]Truck\ 2: 5, 10, 15, 20, 25, \ days.....[/tex]
Write out the common days;
[tex]Day = 15[/tex]
The next time they both visit is the after 15 days