The amount of money with the father = Rs 35,000. Deposit required is equal to 20% of the cost of car. If the father deposits Rs 35,000 as a deposit, it means Rs 35,000 = 20 % of cost of car.
Hence the cost of car = Rs 35,000 divided by 20% = Rs 35,000 * 100/20
= Rs 1,75,000