Correct Answer: 142.5

Solution : Average of B (Y 1 and Y 2 ) = $\frac{\text{Production B in Y1+Production B in Y2}​}{2}$
Average of A (Y 3 and Y 4 ) = $\frac{\text{Production A in Y3 + Production A in Y4}​}{2}$
Sum of averages = Average of B (Y1 and Y2) + Average of A (Y3 and Y4)
Now, Average B (Y1 and Y2) = $\frac{75+90}{2}$ = $\frac{165}{2}$
Average A (Y3 and Y4) = $\frac{70+50}{2}$ = $\frac{120}{2}$
So, the sum of averages = $\frac{165}{2}+\frac{120}{2}$
= $\frac{285}{2}$
= 142.5
Hence, the correct answer is 142.5.