Someone pls help me and explain

Find the vertex for the parabola given by the function ƒ(x) = −3x2 − 6x.

Whoever gets this right gets the ! the half life of a soul smelling substance is 4 years. if you have 8 oz of this strange substance, how much of it will you have after 20 years? show work.

Hart manufacturing had six-month sales of $80 million, with $20 million of that amount from the internet. it set a goal to increase the percentage of total sales coming from the internet by 4 percent in the next six months. the results were total sales of $85 million. if the company meets its goal exactly, what will the dollar amount of internet sales be?