Question 1208482
Maybe you can use Desmos on your own, but description feels like you want an equation for finding 
profit for a number of lawns served.  The cost of the lawn mowers just happens once.  The revenue
from the lawns would happen more than just once, so this formula may be incomplete:


x, number of lawns
y, the profit


{{{y=10x-1x-450}}}

{{{y=9x-450}}}