A manufacturer has to ship 150 washing machines to a neighboring town. Upon inquiring he found that two types of trucks are available.

A manufacturer has to ship 150 washing machines to a neighboring town. Upon inquiring he found that two types of trucks are available. One type will carry 18 machines and the other will carry only 13. The cost of transporting a large truckload is $35 and the cost of for a small truckload is $25. What is the most economical way to ship the machines?