GCSE maths practice paper questions if anyone could help I'd be v v greatful :)

Which best explains why this triangle is or is not a right triangle?

For which of the following counts would a binomial probability model not be reasonable? a)the number of people in a classroom born in januaryb) the number of people in a classroom with red hair c) the number of people admitted to a hospital in a day with a particular disease d) the number of heart beats in a one-minute perio.

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10