tolong dibantu caranya ya teman2 ....

I.) 40 × 10 = 400 dm2

II.)
[tex] \frac{40 + 20}{2} \times t = \frac{60}{2} \times 13 = 390 \: {dm}^{2} [/tex]
III.) 1/2 × a × t
= 1/2 x 40 × 20 = 400 dm2

400 dm2 + 390 dm2 + 400 dm2
= 1.190 dm2 (c)