For a system of equations such as this, add both of the equations together. The d values will cancel each other out, making 2e=-4. This means that e=-2. If you plug this into one of the equations, you will have d + (-2) = 1. Isolate the variable by adding -2 to both sides: d=3. Written in the format described above (d,e), your answer is (3, -2).
The first one is true. Plugging in 1000 units for x gives c(x) = 200000, which is the minimum the company can sell it for while still making a profit.
It can't be the maximum as the company will want to make a profit.
The third and fourth have mathematical errors. Both will equal 0 and not 800000.
The answer would be a 28% decrease.
Hope that helps!!
(32°) = 1700 feet / x => x = 1700 feet / tan(32°) = 1700 feet / 0.625 = 2720 feet.