A swim race has a total distance of 30 mi. Race officials want to mark the course every 825 yd with a buoy, including one at the finish line. How many buoys are needed?

12

step-by-step explanation:

a triangle's   full angle is 180 degrees so 180 - 156 = 24. 24/2=12

check above link.

graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.

you would 18 *0.25 = 4.5