Explanation:
Let the number of packages delivered by Ralph's Express be x.
The number of packages delivered by Speedee Delivery would then be 4x.
The number of packages delivered by Send Quick Package Service would be x-5.
Adding all of these together,
x + 4x + (x - 5) = 6x -5
6x - 5 = 55
6x = 60
x = 10
Hence,
Ralph's Express delivered 10 packages.
Speedee Delivery delivered 40 packages.
Send Quick Package Service delivered 5 packages.