Nice Area Problem (1)

The area of triangle $A =\frac{3\times1}{2}=1.5$ .

The area of triangle $B= \frac{2\times 2}{2}=2.0$ .

The area of triangle $C=\frac{3\times2}{2}=3.0$ .

The area of triangle $D=\frac{2\times1}{2}=1.0$ .

Adding all these Areas of triangles A, B, C and D is $7.5$ , where the area of the big blue square is $5\times5=25$ .

Thus, the ratio of the area of the triangles to the area of the square is $\frac{7.5}{25}=\frac{30}{100}= 30\%$ .