The answer to the question is A
Answer:
The value is 
Step-by-step explanation:
Generally the productivity rate is mathematically represented as

Here K is the ha the farmer could harvest in an hour and Z is a typical yield of corn in kg/ha
Now considering 1970
The productivity rate is

=>
Now considering 1940
The productivity rate is given as
Generally the productivity ratio is mathematically ration is mathematically represented as

=> 
=> 
3/4 of an hour = 45 minutes
45 * 3 = 135 minutes
135 + 45 = 180 minutes
He spends 180 minutes or 3 hours
Using a savings interest calculator, I found that either way your savings grow by exactly $1,020.20, so they share the same interest.