Find the slope on the line

Really need on these. i have no idea what to do

Shared decision making is always a positive strategy to take

The half-life of a certain material is 0.004 second. approximately how much of a 20-gram sample will be left after 0.016 second? a. 5 grams b. 16 grams c. 0.32 gram d. 1.25 grams