A student has to sell 2 books from a collection of 6 maths, 7 science, and 4 economics books. How many choices are possible if
1.1) both books are to be on the same subject?
1.2) the books are to be on different subjects?

Calculate the density of benzene if 300ml of it weighs 263g. a. 0.88 g/ml b. 1.14 g/ml c. 78,900 g/ml d. 37 g/ml

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days

Which of the following parabolas opens down?