First you need to know that there was a base of $20.95.
And an additional .92 cents for EACH mile driven.
When he returned the truck, the total was $291.43.
First you need to subtract the base from the rest
$291.43 - $20.95 = $270.48
Now you divide the remainder by 0.92c
$270.48\0.92c = 294
Chai drove for 294 miles