1. You know that the triangle described in the problem is a right triangle and the problem gives the length of the opposite side. Therefore, you can calculate the lenght of the hypotenuse as following:
Where:
2. When you substitute the values above and solve for the hypotenuse, you obtain:
The y intercept is the constant. She doesnt give that amount of money every month because there are x amount of months. That means the 75 is how much she puts in the account each month. So the answer would be B.