Lithium borohydride $\left(LiB{H}_4\right)$ is a useful reducing agent, as it is more selective that LAH but less selective than $NaB{H}_4.$ Unlike the later, $LiB{H}_4$ will reduce esters. However, it will not reduce amides. This selectivity is frequency employed by synthetic organic chemists. In the following reaction sequence, 51.9 gm of product (3) is obtained with yield of 65% and 75% respectively in 1^st and 2^nd steps. Find the number of moles of reactant used in this reaction?  $(C=12,O=16,N=14,H=1)$