HI I really need help with this its in the picture

Explanation:
The blue rectangle has area of 4a^2*6a^2 = 24a^4
The red rectangle has area 4a^2*9a = 36a^3
The green rectangle has area 4a^2*3 = 12a^2
The total area is 24a^4 + 36a^3 + 12a^2