Question $2$

Refer to the screenshot below:

Using proper cell locations, what is the formula for the LHS of the $1^{st}$ Constraint?

$$ A$.=C{11}^{**}C9+D{11}^{**}D9$

B$.=C{9}^{**}C4+D{9}^{**}D4$

C$.=C{9}^{**}C6+D{9}^{**}D6$

D$.=C{10}^{**}C4+D{10}^{**}D4$