Answer:
The answer is 75 and 85.
Step-by-step explanation:
If the instrument measures in units of 10, then the measurement could be 5 units on either side of 80 (80 − 5 = 75, 80 + 5 = 85). Any value between 75 and 85 would be measured as 80.
if you've read those links already, you'd know what we're doing here.
we'll move the repeating part to the left-side of the dot, by multiplying by "1" and as many zeros as needed, or 10 at some power pretty much.
on 0.13 we need 100 to get 13.13.... and on 0.1234, we need 10000 to get 1234.1234....
![\bf 0.\overline{13}~\hspace{10em}x=0.\overline{13} \\\\[-0.35em] ~\dotfill\\\\ \begin{array}{|lll|ll} \cline{1-3} &&\\ 100\cdot 0.\overline{13}& = & 13.\overline{13}\\ 100\cdot x&& 13 + 0.\overline{13}\\ 100x&&13+x \\&&\\ \cline{1-3} \end{array}\implies \begin{array}{llll} 100x=13+x\implies 99x=13 \\\\ x=\cfrac{13}{99} \end{array} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ 0.\overline{1234}~\hspace{10em}x=0.\overline{1234} \\\\[-0.35em] ~\dotfill](https://tex.z-dn.net/?f=%20%5Cbf%200.%5Coverline%7B13%7D~%5Chspace%7B10em%7Dx%3D0.%5Coverline%7B13%7D%0A%5C%5C%5C%5C%5B-0.35em%5D%0A~%5Cdotfill%5C%5C%5C%5C%0A%5Cbegin%7Barray%7D%7B%7Clll%7Cll%7D%0A%5Ccline%7B1-3%7D%0A%26%26%5C%5C%0A100%5Ccdot%200.%5Coverline%7B13%7D%26%20%3D%20%26%2013.%5Coverline%7B13%7D%5C%5C%0A100%5Ccdot%20x%26%26%2013%20%2B%200.%5Coverline%7B13%7D%5C%5C%0A100x%26%2613%2Bx%0A%5C%5C%26%26%5C%5C%0A%5Ccline%7B1-3%7D%0A%5Cend%7Barray%7D%5Cimplies%20%5Cbegin%7Barray%7D%7Bllll%7D%0A100x%3D13%2Bx%5Cimplies%2099x%3D13%0A%5C%5C%5C%5C%0Ax%3D%5Ccfrac%7B13%7D%7B99%7D%0A%5Cend%7Barray%7D%0A%5C%5C%5C%5C%5B-0.35em%5D%0A%5Crule%7B34em%7D%7B0.25pt%7D%5C%5C%5C%5C%0A0.%5Coverline%7B1234%7D~%5Chspace%7B10em%7Dx%3D0.%5Coverline%7B1234%7D%0A%5C%5C%5C%5C%5B-0.35em%5D%0A~%5Cdotfill%20)

Answer:
(2,-5)
Step-by-step explanation:
Reflecting (2,5) across x-axis will invert it's y-coordinate and will make it negative.
24 cm would be my answer to this.
Hope this helps! -Jentri