1. To answer back : टका सा जबाव देना या पलट जवाब देना
We should not answer back our elders.
2. To back out : मुकर जाना, जबान से पीछे हटना
The party has backed out of the agreement at the last moment.
3. To back sb/sth up : समर्थ करना, to support
A mother should not back her son up for his wrong deeds.
4. To bank on/upon : निर्भर होना, depend on
I always bank on your advice