Solve a = p + prt for r solving formula for one of its variables

Which of the following is true for the relation f(x)=2x^2+1

Liz is shipping a package to her friend.the maximum weight of a medium flat-rate box is 20 pounds,including the box which weighs 6 ounces.write and solve an inequality to describe the possible weight ,w, of the contents that liz will ship to her friend if she must use a medium flat-rate box.

What is the absolute value of the complex number -4-sqrt2i