Answer: 60 meters
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Step-by-step explanation:
The triangles are similar triangles (which can be proven with the angle angle theorem), so we can set up the proportion below
140/80 = 105/d
This proportion has us divide each corresponding side over one another in the same order. In this case, I'm dividing the larger triangle's sides over the smaller.
Cross multiply to solve
140/80 = 105/d
140d = 80*105
140d = 8400
d = 8400/140
d = 60