7. Carol sells two types of PC monitors. She sold a total of 14 monitors last month. One model sells for $280 and the other sells for $435. If the total sales for the 14 monitors was $5,160, determine the number of each type of monitor she sold.
8. The sum of two positive numbers is 34. If twice the fist number minus the second number is 29, find the two numbers.
14. There are three routes that a delivery service can take to reach a certain city. The total mileage for the three routes is 720 miles. If the third route is 40 miles less than the sum of the first two routes, and the first and second routes are equal in distance, find the number of miles in each route.
15. Xian divided $19,000 into three investments: a savings account paying 8% annual interest, municipal bonds paying 9%, and high-risk stocks paying 15%. The annual interest from the three investments was $1,780. The amount put in the savings account was $3,000 more than that invested in stocks. How much money did Xian put in each of the three kinds of investments?