Do the task with the excel or manually if possible,thx If a family who owns a food stall is planning to buy a car in the next 3 years for $13920,89. The family is able to set aside 20% of their income...

Do the task with the excel or manually if possible,thx If a family who owns a food stall is planning to buy a car in the next 3 years for $13920,89. The family is able to set aside 20% of their income from $1392,09/month by saving (1% bank interest/month). Is that money enough to buy a car? If not, how much should the family add?