In a certain school, course grades range from 0 to 100. adrianna took 4 courses and her average course grade was 90. roberto took 5 courses. if both students have the same sum of course grades, what was roberto's average?

72, because 360/4 courses = 90 as an average for Adrianna. This means that 360/5 courses equals 72 for roberto.

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.