We have to use Pythagorean theorem that says :

The missing length of the triangle is : 36 feet
Answer:
$633
Step-by-step explanation:
You multiply the 12x15 feet by 31.65
You will save $9
Convert 20% to decimal
Each % is 0.01 so 20×0.01=0.2
Then multiply
45×0.2=9
To do these problems, plug in a couple of values into the equations, and see the general shape of the graph. To ensure you were right, check them on an online graphing calculator. I highly recommend Desmos Graphing Calculator. Cheers!
B inverse you swap x and y