(algebra) linearity

solve (a problem); answer (a question); unravel (a riddle) / comb; untangle (hair)

untie; unravel; undo (a fastening); unwrap / dispel (doubts); clear up (a matter)

to use, make use of, utilize / to adopt, employ / to appoint, assign / to employ, hire / to need

Principle. / A fundamental truth that bases on. / An eternal law that is common over lots of fact. / (philosophy) A basic fact which explains why something exists.

(mathematics) linear

(mathematics) being linear

sex, gender / (grammar) gender

question, problem on homework etc. / a question; a matter (of time etc.) / a problem (something that needs to be dealt with); a trouble / an issue; a matter

(religion) fundamentalism