The slope of the line is -3/4 the top number is the rise and the bottom number is the run. The formula rise/run. U start from point (1,-1) and count 3 up and to 4 to the left which gives you (-3,2). And it’s a negative because you are going to the negative side.
12 inches = 1 foot
11664/12 = 972 feet²
The bedroom has 972 square feet
3 [ (20-4) / 2 ]= 3 * 16/2= 3 x 8 =24
5,(9)=5 9/9= 54/9=6
6/8/4= 6/2=3