The amount that should deposit monthly is $164.98
The formula for calculating the compound amount is expressed as:
[tex]A=P(1+\frac{r}{n} )^{nt}[/tex]
Substitute the given values into the formula to have:
[tex]75000=P(1+\frac{0.075}{12} )^{12(18)}\\75000 = P(1.00625)^{216}\\75000 =P(3.84125)\\P = \frac{75000}{3.84125}\\P= \$19,524.89[/tex]
Hence the amount of money they started with is $19,524.89.
Amount to deposit monthly = 19,524.89/120
Amount to deposit monthly = $164.98
Hence the amount that should deposit monthly is $164.98
Learn more on compound interest here: https://brainly.com/question/24274034