The interest rate on a second mortgage was5 7/8 % last month. This month the interest rate is 7 3/2 %. How many percentage points has the interest rate increased?

Question

Are you sure you mean 7 3/2% ? No lender would write an intereest rate that way.

Perhaps you typed a numerator or denominator wrong. Do you mean 7 1/2%, or 7 3/8 %, for example?

In any case, subtract the "last month" interest rate from the current interest rate to get the answer. This can be done by either decimal conversion or by finding a common denominator for the interest rates.