Answer:
64 ft²
Step-by-step explanation:
10 ft · 10 ft
100 ft²

6 · 6 = 36
36 ÷ 2 = 18
18 ft² + 18 ft² = 36 ft²
100 ft² - 36 ft²
64 ft²
For lines to be perpendicular they would need to have opposite slopes, so for a slope of -3/7 the slope of a perpendicular line would be 7/3
simplified original equation: y=-9/5x+13.2
perpendicular slope: 5/9
equation passing through (-6,8): y-(8)=5/9(x-(-6))
y=mx+b form: y = 5/9x + 14