what do I use to find the answer?

Answer:
164 Yards
Step-by-step explanation:
With the information in this problem, we need to assume that triangle ADE and ABC are similar, otherwise we would not have enough information to solve it.
1. AE/DE=AC/BC (Since the triangles are similar, the corresponding parts will have the same ratio. In other words, you should be able to multiply the length of any side in one triangle by the same number and get a side length of the similar triangle.)
2. AE/DE=(AE+EC)/BC (Rewrite side length AC as the sum of its parts)
3. 230/120=(230+85)/BC (Insert the values given for each side length into the equation)
4. 230/120=315/BC (Add 230 and 85)
5. 230*BC=315*120 (Cross multiply)
6. BC=315*120/230 (Divide each side by 230 to isolate BC)
7. BC=164.347826... (Plug the equation into a calculator)
8. BC=164 (Since the problem asks to round to the nearest yard and the number in the tenths place is below 5, round your answer down to 164)
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please lmk if i made any errors, hope this helps!!!