So what I did was the terms that were alike like this: (5x -19x)+(20y+36y)+4.27xy+9.11. Then I simplified and got -14x+56y+4.27xy+9.11. The terms 4.27xy and 9.11 were not in ()'s because they were the only ones with an alike term. Hope that helps and also try to doing the steps and see what you get. If you get it wrong look to see where you messed up and try again! If I am wrong please notify me, I would appreciate it!
20000=p(1+0.05/12)^12*9
Solve for p
P=20,000÷(1+0.05÷12)^(12×9)
P=12,764.49
20% of $175 is $35. Divided between 5 people (35/5=7) would be 7. So each person should tip $7.
Acute angles because they are less then 90 degrees which is a right angle.
