AMC 8 1988 Problem 18

The average weight of $6$ boys is $150$ pounds and the average weight of $4$ girls is $120$ pounds. The average weight of the $10$ children is $\text{(A)}\ 135\text{ pounds} \text{(B)}\ 137\text{ pounds} \text{(C)}\ 138\text{ pounds} \text{(D)}\ 140\text{ pounds} \text{(E)}\ 141\text{ pounds}$