John walked from town A to Town B at a uniform speed of 4km/hr. When he reached town B ,he was turned back immediately and he walked back to town A along the same road at a uniform speed of 6km/hr. What is his average speed for the whole trip?​

Empty box + box + empty box fill in the box is equal to 30 how

Which expression do you get when you eliminate the negative exponents of 4a^2 b^216a^-3 b

Martha has a deck of cards. she has lost some of the cards, and now the deck only contains nine spades, eleven diamonds, eight clubs, and twelve hearts. martha predicts that whenever she draws a card from the deck without looking, she will draw a club one-fifth of the time. which activity would best allow martha to test her prediction? a. randomly draw a card from the box and see if it is a club. b. randomly draw a card. then, continue to draw another card until all eight clubs are drawn. c. randomly draw and replace a card 120 times. then, observe how close to 30 times a club is drawn. d. randomly draw and replace a card 100 times. then, observe how close to 20 times a club is drawn.