Learning goals: Teacher Facing Comprehend “interest,” “markup,” “markdown,” and “commission” as other contexts that involve adding or subtracting a percentage of the initial amount. Determine the original dollar amount before a markup, markdown, or commission. Explain (orally) how to calculate the new dollar amount after a markup, markdown, or commission. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from 7.4 Proportional Relationships and Percentages, Grade 7.