PLZ HELP !! Identify the number of the first step where a mistake occurs, if any and show what it should look like.

The sum of two numbers is 12 and their difference is 18 what are the two numbers

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)

What are the values of each variable in the diagram below?