If there were 200 students who passed an English course three years ago, and each subsequent year until the current one that number increased by 50% of the previous year's number, how many students will pass the course this year?
We begin 3 years ago with 200 students, and moving forward to two years ago we find there were 200*1.5= 
<gadget id="calculator">200*1.5</gadget>
<output>300</output>
300 students who passed.
At the end of the subsequent year 50% more students pass than last year's 300, so that means 300*1.5=
<gadget id="calculator">300*1.5</gadget>
<output>450</output>
450 students pass.
At the end of the current year there's another 50% increase over the previous year, meaning we have 450*1.5= 
<gadget id="calculator">450*1.5</gadget>
<output>675</output>
675 students pass.

<result>675</result>