fix(challenge-md): Fix file names and preserve challenge order in meta.json

curriculum/challenges/en/08-coding-interview-prep/project-euler/problem-257-angular-bisectors.en.md

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+---
+id: 5900f46e1000cf542c50ff80
+challengeType: 5
+title: 'Problem 257: Angular Bisectors'
+---
+
+## Description
+<section id='description'>
+Given is an integer sided triangle ABC with sides a ≤ b ≤ c. 
+(AB = c, BC = a and AC = b).
+The angular bisectors of the triangle intersect the sides at points E, F and G (see picture below).
+
+
+
+
+The segments EF, EG and FG partition the triangle ABC into four smaller triangles: AEG, BFE, CGF and EFG.
+It can be proven that for each of these four triangles the ratio area(ABC)/area(subtriangle) is rational.
+However, there exist triangles for which some or all of these ratios are integral.
+
+
+How many triangles ABC with perimeter≤100,000,000 exist so that the ratio area(ABC)/area(AEG) is integral?
+</section>
+
+## Instructions
+<section id='instructions'>
+
+</section>
+
+## Tests
+<section id='tests'>
+
+```yml
+- text: <code>euler257()</code> should return 139012411.
+  testString: 'assert.strictEqual(euler257(), 139012411, ''<code>euler257()</code> should return 139012411.'');'
+
+```
+
+</section>
+
+## Challenge Seed
+<section id='challengeSeed'>
+
+<div id='js-seed'>
+
+```js
+function euler257() {
+  // Good luck!
+  return true;
+}
+
+euler257();
+```
+
+</div>
+
+
+
+</section>
+
+## Solution
+<section id='solution'>
+
+```js
+// solution required
+```
+</section>