My maths teacher says 51÷80 is 1r56 how is this possible

Set up and solve a proportion for the following application problem. if 55 pounds of grass seed cover 404 square feet, how many pounds are needed for 7272 square feet?

In which direction does the left side of the graph of this function point? a(x) = 3x - x2 + 4x - 2

Whats are the trickiest steps to do when adding or subtracting rational expressions? how does knowledge of rational numbers u in adding and subtracting rational expressions?