The basic formula is I = P * i * t, where I is interest, P is total principal (or profit), i is rate of interest per year, and t is total time in years. I = P * i * t can be rearranged to solve for t: t = I / (i * p).
In this question I = $6400, P = $3200 and i = 8.25%, so we plug in those numbers to get t = 6400 / (0.0825 * 3200), which solves to 24.2424 years.
The total amount of lawns to be mowed would be 20 in 35 hours.
Step-by-step explanation:
It takes an hour and 45 minutes to mow one lawn. When you multiply the 7 hours by 5 you get 35 hours. Same thing if you multiply the 4 lawns by 5 you get 20 lawns.
