Ialso bought $7$ different postcards. how many ways can i send the postcards to my $3$ friends, so that each friend gets at least one postcard?

how do i count the restriction that each friend must get at least 1 or more postcards and the postcards are distinguishable?

The water company charges a residential customer $41 for the first 3,000 gallons of water used and $1 for every 200 gallons used over 3000 gallons. if the water bill was $58 how many gallons of water were usedanswersa 3400 gallonsb 6000 gallonsc 6400 gallons d 7000 gallons