What is the surface area of a square-based pyramid with a base length of 4 m and a slant height of 5 m?

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?

|z| > (1/2) {-1/2, 1/2} {z|(-1/2) < z < (1/2)} {z|z < (-1/2) ∪ z > (1/2)}

Add: (6x^2-5x+3) + (3x^3+7x-8) a. 9x^2+12x-5 b. 9x^2+2x+11 c. 9x^2+2x-5 d. 9x^2-2x+5