a) The unpaid balance after one year is of: $72,686.36.
b) The interest that they pay during the first year is of: $77,333.33.
Their monthly payments are of:
$609.47.
One year is composed by 12 months, hence the total payments after the first year are given as follows:
12 x 609.47 = $7,313.64.
The unpaid balance is the amount that is left to be paid, hence it is the subtraction of the total loan by the amount paid during the first year, hence:
80000 - 7313.64 = $72,686.36.
Without interest, the amount that they would pay each of the 30 years is obtained by the division of 80,000 and 30 as follows:
80000/30 = $2,666.67.
Hence the amount of interest paid during the first year is of:
80000 - 2666.67 = $77,333.33.
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