Isolating the variable 'a' in the expression, we have:

So the correct option is B.
Two points give you a line. A third point (often called a check-point) is used to confirm the accuracy of your first two points. If all three line up, you have confirmed you have the correct line.
Answer:
all work is shown and set
Answer:
probability of bag one 62.5% for blue marbles green- 37.5%
probability of bag 2 66.67% for yellow and for blue 33.33%
he will probably get a blue and yellow marble
:)