Difference means subtraction 14,505-282=14,223ft
Permutation: In a race of 10 students, find the number of ways students can finish 1st, 2nd, and 3rd. In this case the order matters, so it is a permutation.
10 x 9 x 8 = 720 ways
Combination: In a class of 10 students, find the number of ways a group of 3 students can be selected to win a prize. In this case the order doesn't matter, so it's a combination.
10 x 9 x 8 / (3 x 2 x 1) = 120 ways
Beck add like terms so you get
4x^2 -4x-15
lucy factor our negative so you left with -4x^2 +5x -10 +8x^2 -9x -5
simplify 4x^2 -4x -15
therefore both students answers simplify to 4x^2 -4x -15