So like who want to be friends

Translate the word phrase into a math expression. 15 fewer than the product of 4 and a number. (pls immediately)

Both the red and blue line segments stretch from the center of the circle to a point on the circle. the length of the blue segment is 5. how long is the red line segment?

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