It could possibly be Y = Ax + B, but only if it is a linear (a straight line).
If it is exponential (the line looks like a single ramp), it is Y= A x B^x
If it is quadratic (going both up and down; it looks like either a U shape, a “tree stump” shape or two exponential lines on opposite sides and flipped), it is Y= Ax^2 + Bx + C.
