Consider the following two modular linear equations, which shall be solved for the variable

x: 6 + 4x = 0 (mod 16)

-11 + 7x = 0 (mod 17)

Solve both equations. Provide either the result for x if the equation is solvable or write not solvable if the equation cannot be solved.

Explain one method to compute the multiplicative inverse. It is sufficient to name the method (algorithms/theorems) and show how the inverse is derived from its application.