Find all complex numbers $z$ such that $z^4 = -4.$ Note: All solutions should be expressed in the form $a+bi$, where $a$ and $b$ are real numbers.

You earn a 12% commission for every car you sell. how much is your commission if you sell a $23,000 car?

Boris needs to buy plastic spoons. brand a has a box 42 spoons for $2.37. brand b has a box of 72 spoons for $3.57. find the unit price for each brand. then state which brand is the better buy based on the unit price. round your answer to the nearest cent.

Given that abcd is a rhombus, what is the value of x?