Can anybody help me find out how to get the other marks on this question please?

Answer:
the percentage is 55/100*100=55%
Step-by-step explanation:
the segment of the square is 40/4=10 cm
so the area of the square is 10^2=100cm^2
the shaded area = the area of the square - the sum of the areas of the triangles inside the square
100- (10*6/2+10*3/2)=100-(30+15)=55 cm^2
Answer:
P = 40cm => l = 40 : 4 = 10cm
A(red) = 10*3/2 = 15 cm²
A(blue) = 10*6/2 = 30 cm²
A(grey) = A - (Ar + Ab) = 10*10 - (15+30) = 100 - 45 = 55cm²
(A)100cm² ..............100%
(Ag)55cm²..................x%
Ag = 55*100/100 = 55%