Answer :
Intrest=principal*rate*time
500-350=150<---final interest
150=350*2.8*time
150=980*time
time=approx. 0.15years or 54.75 days
500-350=150<---final interest
150=350*2.8*time
150=980*time
time=approx. 0.15years or 54.75 days