Based on the information given in the question, the increase in the profit will be calculated as the contribution from the 3000 extra units minus the worker's salary.
Contribution from 3000 units will be:
= (Selling price - Direct materials - Direct labor - Variable overhead) × 3000
If a line is parallel to y-axis, the equation of the line is x = constant because it is at a constant distance from y-axis. so for the given question, x = 3 is the equation of the line passing through (3,2).