In an engineering college the average salary of all engineering graduates from Mechanical trade is $\text{Rs. }2.45$ lacs per annum and that of the engineering graduates from electronics trade is $\text{Rs. }3.56$ lacs per annum. The average salary of all Mechanical and Electronics graduates is $\text{Rs. }3.12$ lacs per annum. Find the least number of Electronics graduates passing out from the institute :
- $43$
- $59$
- $67$
- Cannot be determined