Okay so, to solve these problems what you're gonna want to do is substitute the given x and y values into the equation.
For example, number 7.
11(d-c) + 3(c+d), when c=6, d=9
if d=9, you will substitute the d in the problem to 9.
11(9-c) + 3(c+9)
if c=6 you will substitute c for 6.
11(9-6) + 3(6+9)
You can solve now that you have a simpler problem to work with.
11(9-6) + 3(6+9) first...
11(9-6) 11*9=99 11*-6=-66, so, 11(9-6)= 99-66= 33.
3(6+9) 3*6=18 3*9=27 18+27=45
33+45=78
Your answer for number 7 is 78.
Hope this helps, just do the same for the other problems like this one.