In vectors A and B be respectively equal to 3i^−4j^+5k^ and 2i^+3j^−4k^. The unit vector parallel to A + B is 127(5i^−aj^+k^) The value of a is ________
A→+B→=5i^-j^+k^ ⇒Unit Vector=1275i^-j^+k^ ⇒a=1