Hello there. To answer this question, we need to remember some properties in simple and coumpound interests investments.
For simple interest, the balance will be equal to P(1 + rt), in which P is the amount invested, r is the interest rate in years and t is the time (can be either years of months).
For compound interest, the balance will be equal to P(1 + r)^t.
So, using the values P = $19,000.00 and the time is equal to 30 years, we have for:
a) 7% simple interest
It means that r = 7% and then we can use the first formula
19000(1 + 0.07*30)
We converted the rate to decimals above
Multiplying the values, we have:
19000(1 + 2.1)
19000*3.1
$58.900
b) 7% compounded monthly
First, we need to convert the time from years to months, multiplying by 12
30*12 = 360 months
Using the second formula, we have:
19000(1 + 0.07)^(360)
Sum the values into parenthesis
19000*1.07^(360)