First we need to calculate the selling price after 50% increase
selling price = original cost + increase
selling price = 100% original cost + 50% original cost
selling price = 150% original cost
selling price = 1.5 × original cost
selling price = 1.5 × 30
selling price = 45
The selling price after getting a markup is $45
Second, we need to calculate the sale price after markdown 50%
Right now, we use $45 as the original price not $30 to count the sale price
sale price = original price - markdown
sale price = 45 - 50% × 45
sale price = 45 - 0.5 × 45
sale price = 45 - 22.5
sale price = 22.5
The sale price is not $30
