Equation

Write the situation as named variables and a relation between them, so you can compute an answer and watch it move when one input changes. Fits when the quantities are real and measurable; fails when the deciding factors resist measurement.

Write the situation as named variables and a relation between them, so you can compute an answer and watch it move when one input changes. Fits when the quantities are real and measurable; fails when the deciding factors resist measurement.

Example

Instead of arguing which vendor is cheaper, write: three-year cost = seats × price per seat × 36 + onboarding + switching cost. Plug in 120 seats, and Vendor B's $40 seat price loses to Vendor A's $52 once B's $18,000 onboarding lands.