Find the equation of the curve $\displaystyle y=x^2 - 7x^2 + 5$ at the point (1, -1)

Also

One card is selected at random from a pack of 20 numbered 1 to 20. What is the probability that it is either a multiple of 5 or 3. I had 1/2, but apparently its wrong. Please tell where I went wrong.

Thanks