Why are you subtracting 1 in the brackets? Your APR is given in the question so I don't get why you want to work that out. I'd just take a time period of a year and use the compound interest formula below:

The compound interest formula is

Where:

- = amount owed after n compounding periods
- = the initial amount borrowed/owed
- = the nominal annual rate expressed as a decimal
- = number of compounding periods

For offer 1: and

For offer 2: and

In both cases

Plug and chug to see which is lower