Answer:
$600
Equation:
(Base) x (percent as a decimal) x (years) = interest
(B x .16 x 7.5 = 720)
Steps:
(Base) x (percent as a decimal) = (interest) / (years)
(B x .16 = 96)
Base = (interest / years) / (percent as a decimal)
(B = 600)
