Help me with arithmetic sequences.

X=1 2 3 4 5
Y=18. . . . -10

275/20 simplified (lmbo it told me to add more characters)

If mary had 320 toy cars and she gave her friend 50 cars and then she gave her brother 72 more cars how much toy cars would mary have left ● explain with proper details

Officer brimberry wrote 32 tickets for traffic violations last week, but only 4 tickets this week. what is the percent decrease? give your answer to the nearest tenth of a percent.