Since we're looking for time, we can use the formula t = A / Pr, which would be: t = 6000/(7255 x 5.5%) Converting the percentage into decimal form t = 6000/(7255 x 0.055) We can then solve to get: t = 6000/399.025 t = 15.03665183... Meaning it would take 15 years for an interest of 5.5% on $6,000 to reach $7,255. Not very worth $1,255 extra if you need that 6k for rent.