Help with this question please

The difference of two numbers is 40. find the numbers if 0.3 parts of one number is equal to 37.5% of the other one.

In which direction does the left side of the graph of this function point? f(x) = 3x3 - x2 + 4x - 2

Which function has an inverse that is also a function? a.{(-4,3), (-2, 7), (-1,0), (4, -3), (11, -7)} b.{(-4, 6), (-2, 2), (-1, 6), (4,2), (11, 2)} c.{(-4,5), (-2, 9), (-1,8), (4, 8), (11,4)} d.{(-4,4), (-2, -1), (-1,0), (4, 1), (11, 1)}