In equation q note they have a^-1.

In equation a, for each term look at what a^-1 is, and have the standard conduction or convection equations in front of you, bearing in mind that in equation q, a^-1 is multiplied by 4*pi*(0in - 0out)

It should start to become clear what they're getting at!

Good luck

p.s. remember surface area of sphere with radius r is 4*pi*r^2 but think about what the radius is for each part you're looking at and that'll help