Use the rule of 72 to determine how long it takes to accumulate $10,000 in a savings

Question:

Use the rule of 72 to determine how long it takes to accumulate $10,000 in a savings account when P = $5,000 and i = 10% per year.
Rule of 72: The time (years) required to double the value of a lump-sum investment that is allowed to compound is approximately
72 ÷ annual interest rate (as a %).