Do you have an experimentally-determined NMR spectrum for a specific organic compound to which you plan to apply first-order spectral analysis? If so, please provide a copy of the actual NMR spectrum to be analyzed.
Alternatively, is this a hypothetical example in which a single methine proton is coupled simultaneously to adjacent methylene protons (J = 7.32 Hz) and also to two adjacent (magnetically equivalent) methyl groups (J = 6.6 Hz)? If so, it is important to know the chemical shifts of all mutually coupled protons, since the ratio of (delta nu)/J determines whether or not the spin system is amenable to first-order spectral analysis.
And finally, you mentioned that "there is only 5 peaks present". Do you mean 5 peaks in the entire proton NMR spectrum of the compound, or 5 peaks that correspond to one of the proton absorption patterns (perhaps those that correspond to the methine CH proton absorption) in the spectrum?
Clarity, clarity.