Make problem more concise

There is no need to assume X is not zero.
Merge pull request #117850 from bolin-hsu/concise

Remove irrelevant text from problem
Merge pull request #127579 from mauk81/jslint

removed unnecessary comma
I18nize gcf.

Test Plan:
Loaded http://localhost:8080/math/arithmetic/factors-multiples/greatest_common_divisor/e/greatest_common_divisor
and did a problem taking all the hints, making sure that it displays as before (but showing gcf not gcd)

Auditors: eater
Changed \text to \operatorname to take care of nit.

The spacing seemed the same on this either way, but to be more proper I have changed it.

Test Plan:
Loaded http://localhost:8080/math/arithmetic/factors-multiples/greatest_common_divisor/e/greatest_common_divisor
and did a problem taking all the hints, making sure that it displays as before (but showing gcf not gcd)

Auditors: alpert
CC: eater
remove typo

oops, had put that in while testing out spacing differences

Test Plan:
cross-fingers

Auditors: alpert
Merge pull request #128336 from petercollingridge/division

Fix divider hint
Improve hint counts
Fix how hints are counted

close #218336
fix #126549; fix #128535
Mark string for translation

Test Plan: none

Auditors: peter
i18n lint

Apparently we can't have $._() inside vars unless we're defining the var so this is what we do.

Test Plan: make lint in khan-exercises

Auditors: james
removed some unused vars