Find all the zeroes of the equation(with simple steps). -3x^4 + 27x^2 + 1200 = 0 ! urgent!

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?

1.based of the diagrams what is the the value of x? 2.how would you verify your answer for x

4. a single woman uses an online cash flow calculator which reveals a cash flow of 203. what does this mean?