Which of the following best describes the expression 2a + 3b + 4c + 5d?

The product of four sums; there are four terms
The product of four sums; there are eight terms
The sum of four products; there are four terms
The sum of four products; there are eight terms

Find a number such that if you add 8 and divide the result by 4 you will get the same answer as if you subtracted 3 from the original number and divided by 2

How to solve a simultaneous equation involved with fractions?

The number if marbles of different colors stored in a hat is listed below: 4 red marbles 10 green marbles 7 blue marbles. without looking in the hat, dan takes out a marble at random. he replaces the marble and then takes out another marble from the hat. what is the probability that dan takes out a blue marble in both draws?