Good day AMaccy. Step by step it is then
Step 1. Rearrange the line equation into the form y=mx+c
Step 2. Remember that your teacher said,for our line to be parallel to the given line, it must have the same gradient.
Step 3. Gain insight/remember for a line to be tangent to a curve, it must possess the same gradient as the curve at one particular point.
Step 4. Knowing these 2 facts, we state that the gradient of our wanted line is
Step 5. Differentiate the curve to discover where it's gradient is
Step 6. Obtain the y-coordinate at x=
Step 7. We now have the point at which the curve and line touch and our line's gradient, calculate our line's y-intercept.
So the equation of the line is