5 3/7 in improper form is 38/7, the reciprocal means to flip the fraction's numerator and denominator. 7/38 is the reciprocal and cannot be simplified any more.
Yes...Because Reciprocal is basically flipping the numerator and denominator, and That's where 7/3 and 3/7 comes in. noticing that they're flipped proves that this is reciprocal.
