This is what i got:
-x-20=6x+1
X/28 = 5/7
x = 28 * 5 / 7
x = 20
answer
x = 20 ft
The answer to your question is A
5,000 - bag of fertilizer
500 - Mike’s lawn
3/4 - applied fertilizer
4 - frequency in 1 year
(500 x 3/4 )x 4
(1500 / 4 ) x 4
1500 sqm / yr
5,000 sqm / 1500sqm/yr
3.33 yr
He will be able to fertilize it in 3 full years