Solving simultaneous equations using matrices

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 math sentence can be used to determine if the triangle is a right triangle?

Evaluate the expression for the given value of the variable 7a - 4a for a =8