11. RESTAURANT A group of three restaurant patrons order the same meal and drink and leave an 18% tip. Determine functions that represent the
cost of all of the meals before tip, the actual tip, and the composition of
the two functions that gives the cost for all of the meals including tip.

the solution is 12x-6y

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.