according to the rule of 72, in about how many year will $80 be worth $40 if the rate of inflation is 3%

The number of years it will take $80 to be $40 using "the rule of 72" will be 24 years

Explanation:

"the rule of 72" is a method used to estimate the number of years it will take to either double or cut in half a capital by dividing '72' by the given interest or inflation rate.

capital : $80

half capital : $40

rate of inflation : 3%

To calculate N years it took to get $40 = 72/rate of inflation

= 72/3 = 24 years

The rule of 72 is

72/rate=time

72:3=24 years