Answer:
The selected answer is correct (8 cm)
Step-by-step explanation:
So in this problem
we are given that the total length of the composite figure is 14 cm (this including the rectangle's length and the triangle's base length)
We also happen to be given the rectangles length
So we can find the triangles base length by subtracting the total length of the figure by the length of the rectangle
Triangle base length = 14 cm - 6 cm
14 - 6 = 8
Hence the answer is 8 cm
