Answer:
required time=3 year
Step-by-step explanation:
simple interest=[tex]\frac{P\times R\times T}{100}[/tex]
where P=principle
R=rate of interest
T=time
totel amount=principle+interest
interest=totel amount-principle
interest=$221-$200=$21
ac/ques, 21=[tex]\frac{200\times 3.5\times T}{100}[/tex]
21=[tex]7\timesT[/tex]
T=3 year
