Answer:
firm deposit  is $1667.50
Step-by-step explanation:
given data
buys 12 file = $140
time = 90 days
interest = 3%
solution
we get here return on money over 90 day period  is Â
we know Return on 360 days = 3%
return on money over 90 day = 3% ÷ 4  = 0.75%
we consider here required amount = x
so
$140 × 12 = x (1+0.0075)
x  =  [tex]\frac{1680}{1+0.0075}[/tex]
x = 1667.50
so firm deposit  is $1667.50