What is happening between the two steps?

9 + 10x - 5x = -31

9 + 5x = -31

Fiona and her friends are playing a game by guessing where a coin will land when it is randomly dropped inside the square shown below. fiona guesses that the coin is likely to land in the blue area. which explains whether or not fiona is correct and why?

Which fraction below is equivalent to 10/12?

Twice the sum of a number and 4 is equal to three times the difference of the number and 7. find the number.