Me i really don't want to get at tell me if it's a b or c weather guess who i get a lot of points in a brain list

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

Solve for x and y: 217x + 131y = 913; 131x + 217y = 827

How many kilograms of a 5% salt solution and how many kilograms of a 15% salt solution must be mixed together to make 45kg of an 8% salt solution?