<h2>Answer:</h2>
The Slope is 
<h2>Explanation:</h2>
Notice that both the points,
and
, are on the line. So we can use those points to calculate the slope. Recall that that slope of the line
can be calculated by
if we have the points,
and
.
<h3>Calculating for the slope of the line:</h3>
Given



Do you mean checking your work? In that case it would be 9*20.
Multiple 15 by 6, the answer is 90 square cm