Gabriel, Aditya, Sam

Calculus Level 1

Three friends $Gabriel, Adtya, Sam$ were having three different equations with them.

$Gabriel$ is having the equation: $y=8x+4$

$Aditya$ is having the equation: $y=4x+2$

$Sam$ is having the equation: $y=3x+1$

Find the sum of the $\frac{dy}{dx}$ of this three friends equation...