As determined by the graph, f(-9) = 9
If the amount of time taken to go said distance is x and the amount of time taken to go back said distance is y, then the amount of miles total is 7x+3y due to that for every hour, she adds 7 miles when going there and 3 miles for walking back. In addition, since the total amount of time is 4 hours, x+y=4 as the total time spent as well as 7x=3y due to that they're the same distance.
x+y=4
7x=3y
Dividing the second equation by 7, we get x=3y/7. Plugging that into the first equation, we get 3y/7+y=4=10y/7 (since y=7y/7). Multiplying both sides by 7 and then dividing both by 10, we get 28/10=2.8=y in hours. Since 0.1 hours is 60/10=6 minutes, and 0.8/0.1=8, 6*8=48 minutes=0.8 hours, meaning that she should plan to spend 2 hours and 48 minutes walking back
9:45 + 10 = 9:55
9:55 + 2:00= 11:55 This is what I got
Since they are similar, you need to find the ratio of similarity (I made up the term, there is probably a correct one that I can’t remember).
If you divide 16/40, you’ll find that that ratio is 2.5. So then you just multiply 16 x 2.5. You’ll get 18.
18 is the length of the top of the trapezoid.
You set 18=2x+4 and solve it algebraically. Subtract 4 from both sides.
14=2x
Divide by 2 and x=7
(You can also check that the ratio is right by 16/18 is the same decimal value as 40/45. You’ll get .88888...)
