Answer:
based on my experience mind you're answer.
4.9 * 102 = 499.8
6.8 * 103 = 700.4
1.71 * 103 = 120.51
8x6= 48 (not necessary to divide by 8 since you'd have to multiply it by 2 anyway because there are 2 triangles)
6x12=72
10x12=120
12x8=96
48+72+120+96=336
336cm^2 is the answer