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

by use of the formula A = P (1 + rt) where : A is the final amount = 542 + 303.52 = $ 845.52

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)

open the bracket = $845.53 = $542 + $37.94 t

like terms together

=$ 845.53 - $542 = $37.94 t

=$303.52 = $37.94 t

divide both side by $37.94

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

t = 8 years