a ) Car costs in year 2010 : $17,000

cost of car in year 1980 = P.

Cost P of cars increased at the rate 164.68% over the whole of (2010-1980) = 30 years.

Inflation or increase in the price of car = P * 164.68% in 2010 over the price in 1980

Total price of car in 2010 = Price in 1980 + P* 164.68/100

= P + P * 1.6468 = P * 2.6468

= $ 17,000

P = $ 17,000/2.6468 = $ 6, 422.85

b) A pair of jeans cost $ 80 in 2010

Inflation rate is 66.8 % between 1990 and 2010, with the base rate being the cost price in 1990. That means the price increased by 66.8% in 20 years from 1990.

Cost price in 1990 = CP let us say

Increase in price due to inflation: 66.8 % of CP

= 66.8/100 * CP = 0.668 CP

Cost price of jeans in 2010 = CP + increase due to inflation

= CP + 0.668 CP = 1.668 CP

So 1.668 CP = $ 80

CP = $80/1.668 = $ 47.96 or $ 47 rounded off.