PLEASE HELP: PART 1

Lisbeth runs on the track team. After practicing for 4 weeks, she lowers her time in the 800 meter run by 20 seconds.

Which expression can you use to calculate the average change in seconds per week?

A.-800÷4

B.-20÷4

C.20÷4

D.800÷4

Part 2

Evaluate the expression that represents the scenario.
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