D is the amount
n is the number of days
[tex]D_{n=1} = 475\\D_{n=2} = 475 + (.75* 475)\\D_{n=3} = 475 + .75(475 + (.75 * 475))\\D_{n=3} = 475 + .75*475 + .75^{2} * 475\\D_{n} = 475 + .75*475+.75^{2}*475... +.75^{n-1} * 475[/tex]
So therefore:
[tex]475 * \sum_{n=1}^{\infty} 0.75^{n-1} = D_{n}[/tex]
See attached images for a similar problem from Chegg
