Не How many different arrangements of 7 letters can be formed if the first letter must be W or K (repeats of letters are allowed)?

Olga used 100 ounces of flour to make 225 muffins. how many ounces of flour will be used to make 300 muffins?

The u-drive rent-a-truck company plans to spend $13 million on 320 new vehicles. each commercial van will cost $25 comma 000, each small truck $50 comma 000, and each large truck  $80 comma 000. past experience shows that they need twice as many vans as small trucks. how many of each type of vehicle can they buy?

Awasher and a dryer cost $701 combined. the washer costs $51 more than the dryer. what is the cost of the dryer?