Just need with these questions 16,20 24,25 need fast

Joel wants to buy a new tablet computer fram a store having a 20% off sale on all tablets. the tablet he wants has an original cost of $190. he also wants to make sure he has enough money to pay the 5% sales tax. part one joel uses the incorect expression 0.95(190)(0.8) to calculate that the tablet will cost him a total of $144.40. describe his error and write the correct expression part two how much will joel pay for the tablet show your work if you answer this question correctly you will receive a prize of 99 points good luck

State one method by which you can recognize a perfect square trinomial.

Tobias gold sells computers at the office center he's guaranteed a minimum salary of $1,959 per month plus 6.3% commission on total sales how much in total sales is he