-21 = 4x + 7
It's those 2 step equations please explain how to do it thank you.

Find the solution of system of equation y= x-4 y=4x+2

If the table of the function contains exactly two potential turning points, one with an input value of –1, which statement best describes all possible values of m? m ≥ –12 –12 < m < 4 m ≤ 4 m ≥ 4 or m ≤ –12

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)