Since 1989, Lily has treated herself to 1 hydrangea plant, each year.  Each plant costs $20.00.  By 2021, how much money has Lily spent on hydrangeas?
She started buying plants in 1989 and it's now 2021 so she has bought these plants for 2021-1989 = 
<gadget id="calculator">32</gadget>
<output>32</output>
32 years.
Each plant costs $20.00 and she has bought them for 32 years so she has spent 20*32 = $
<gadget id="calculator">20*32</gadget>
<output>640</output>
640.00 on hydrangeas.

<result>640</result>