Mariano is investing in a 401(k) that promises 6.99% annual growth. He plans on investing $150 each month for 32 years (there is no employer matching). Excel calculates an overall account balance of $213,804.83. How much of Mariano's balance is interest?
a) $155,804.83
b) $63,804.83
c) $213,804.83
d) $32,400