Answer: 7.5 quarts of varnish are required for 25 cabinet doors.
Explanation:
4 liquid quarts = 1 liquid gallon
A cabinet maker used 0.75 gallons of varnish on 10 cabinet doors. Converting 0.75 gallons to quarts, it becomes
4 × 0.75 = 3 quarts
Therefore, if the cabinet maker uses 3 quarts of varnish for 10 doors, then the quarts of varnish required for 25 cabinet doors would be
(3 × 25)/10 = 75/10 = 7.5 quarts of varnish.