Number of Fringes in a Diffraction Maximum In Fig. 36.12c the central diffraction maximum contains exactly seven

Question:

Number of Fringes in a Diffraction Maximum In Fig. 36.12c the central diffraction maximum contains exactly seven interference fringes, and in this case d/a = 4.
(a) What must the ratio d/a be if the central maximum contains exactly five fringes?
(b) In the case considered in part (a), bow many fringes are contained within the first diffraction maximum on one side of the central maximum?