The mean of a dataset is the all members of the dataset added together and then divided by the number of members in the set. From your description of the number line, I've created a list of members.
16, 17, 17, 17, 17, 19, 19, 19, 19, 21, 22, 22, 23, 25
Adding all members of this set up produces the value 273. There are 14 members in the set, so 273 / 14 = 19.5. Thus, the mean of the set is 19.5
First one simplifies to 2x + 6 = 2x + 7 which can't be true so this one has No Solution.
Same applies to the second equation ( 5x + 15 = 5x - 15) No solution
also the last one has no solution because it simplifies to 4x + 20 = 4x + 19
Yellow: 25.71% chance of you grabbing a yellow jelly bean
Green:34.29% chance of you grabbing a green jelly bean
Red: 40% chance of you grabbing a red jelly bean
Letter A is the answer because
4y = 15 - 3x
so y = 15/4 -3x/4
431.2+826.4d=2910.4
431.2 is only the first day therefore it doesn't need the variable because the variable represents the number of days. 826.4 even says "each remaining day" referring to what the variable represents.
