Question

Is twice a number subtracted from four times a number,added to 15 linear or nonlinear?

Answer 1

Let's put the statement into Mathematical form first:
It is: 4x - 2x + 15
= 2x + 15

Here, the difference of two output values would be same, so it will be a Linear Equation

Hope this helps!

Answer 2

Simplest expression: 2x + 15

It is Linear