Solve x/5 = 10/5. Find x.

Multiply 5 on both sides of the equation to arrive at x = 50/5. Therefore, x = 10. Proportions are used to find ratios on either sides of the equation. This equivalently finds the value of x to have the same ratio on both sides of the equation.

Why should we learn a Thevenin Equivalent circuit model?

This allows a complex component of circuitry to be modeled as a simple voltage source and a series resistor. This allows someone to visualize the circuitry as a black box and and only need to worry about the input and output of the system.

Solve 5 + x = 6. What is the value of x? What is the meaning of the variable x?

Subtract 5 from both sides of the equation to cancel out 5 from the left hand side. Arrive at X = 1. The variable x represents a variable that is unknown, this is the variable that we seek to make the equation true.