Answer: B) 39
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Step-by-step explanation:
Equilateral triangles have three equal sides, ie the sides are all the same length.
Let's set sides ST and TU equal to each other and solve for x
7x-10 = 2x+25
7x-2x = 25+10
5x = 35
x = 35/5
x = 7
Then we use this to compute each side
- ST = 7x-10 = 7*7-10 = 49-10 = 39
- TU = 2x+25 = 2*7+25 = 14+25 = 39
- US = x^2 - 10 = 7^2 - 10 = 49-10 = 39
Each side is 39 units long, so this confirms we have the correct answer.