For diffraction

Location of 1^st minima

${\mathrm{y}}_1=\frac{\mathrm{D\lambda }}{\mathrm{a}}=0.2469\mathrm{D\lambda }$

Location of 2^nd minima

${\mathrm{y}}_2=\frac{2\mathrm{D\lambda }}{\mathrm{a}}=0.4938\mathrm{D\lambda }$

Now for interference

Path for interference

Path difference at P.

$\frac{\mathrm{dy}}{\mathrm{D}}=4.8\mathrm{\lambda }$

Path difference at P.

$\frac{\mathrm{dy}}{\mathrm{D}}=9.6\mathrm{\lambda }$

So orders of maxima in between P and Q is

5, 6, 7, 8, 9

So 5 bright fringes all present between P & Q.