Step-by-step explanation:
Principal Amount = [tex]P[/tex] = [tex]\$3500[/tex] .
Simple Interest Rate = [tex]6.5\%[/tex] .
[tex]Total\textrm{ }Amount=Principal+Interest=P+P\times i\times T[/tex]
Here [tex]T[/tex] is the Time period which is 18 years.
[tex]\textrm{Total Amount = }\$3500+(\$3500)\times(6.5\times \frac{1}{100})\times (18yr)=\$7595[/tex]
∴ Total Amount in the savings account when their son gets 18 years old = [tex]\$7595[/tex]