How long must $542 be invested at a rate of 7% to earn $303.52 in interest

The number of years that must be invested at  a rate of 7 % to earn$ 303.52 in interest is

    8 years

 calculation

                   P  is the principal   money to be invested =  $ 542

                       r= rate= 7/100=0.07

                      t=  time required

=$ 845.52=$ 542( 1+  0.07 t)

    =$  845.53 -$542  = $37.94 t

   =$303.52 =$37.94 t

  =  $303.52/ $   37.94  =  $37.94t/$37.94

  t=  8 years

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