Marta works on her grandparent's farm to raise money for a new phone. So far, she has collected $240. For every hour she works, she receives $10. Her grandmother often gives her tips, and she has collected $50 in tips in total. How many hours has Marta worked on the farm so far?
Ignoring tips, Marta earned $240 - $50 = $
<gadget id="calculator">240-50</gadget>
<output>190</output>
190.
Therefore, she has worked 190 / 10 = 
<gadget id="calculator">190/10</gadget>
<output>19</output>
19 hours.

<result>19</result>