Question

Please help (click to veiw photo)

Answer 1

M - n 
m = 300x + 100, so we substitute that into the equation for m. 
300x + 100 - n 
n = 250x + 200, so we substitute that into the equation for n. 
300x + 100 - 250x - 200 
Subtract the 250x to get: 
50x + 100 - 200 
Subtract the 200 to get: 
50x - 100, which is option D. 
Hope this helps!