Let's solve the problem step-by-step using the given statements:
Objective: Find the tens digit of a positive integer 'a'.
Statement 1: When 'a' is divided by 100, the remainder is 20.
Statement 2: When 'a' is divided by 105, the remainder is 20.
Conclusion: Based on the analysis above, Statement 1 alone is sufficient to find the tens digit of 'a'. Therefore, the correct answer is:

The pie-diagram below shows the percentage of expenditures of Paul and Balu per month.

If the price of a commodity increases by 25%, by what percentage should the consumption be reduced to keep the expenditure the same?