3. Find the base of a rectangle of height 7 m and whose area is three times the length of its perimeter. 4. A 22-year-old father has a 2-year-old son. Within how long will the father's age be three times that of the son?

1. Assign varibles, write an equation and solve.

15. A rectangular turtle pen is 5 feet long by 3 feet wide. The pen is enlarged by increasing the length and width by an equal amount in order to double its area. What are the new dimensions of the turtle pen?

7. The cost of a square artwork of length x cm is $(x² + 4x). If an artwork costs $300, what is its length?