Hello there!
The answer is 13 trust me. the answer should be 29 for no reason. but answer 13 and you'll get it right.
I don't know how to take a screen shot and post. but the easy way is to count . so 50 years old = 15. 60 years old = 8. 70 years old = 4. 80 years old = 2. add them.
6/7 of 1 3/4......turn the mixed number to an improper fraction...and " of " means multiply
6/7 * 7/4 = 42/28 = 1 1/2...so a compact car weighs 1 1/2 tons or 1.5 tons
The rate of change on the line is x line goes to the right and y line goes upward