Simple...
you have:
1.) x-3y when x=-4 and y=9
-->>> (plug it in)
-4-3(9)
-4-27
-31
2.) a-|b| when a=-7.6 and b=-8.9
-->>>(plug it in)
-7.6-|-8.9|
-16.5
3.) 3(8x-y) when x=-4 and y=9
-->>(plug it in)
3(8(-4)-9)
3(-32-9)
3(-41)
-123
4.)
when c=2 and d=
54
Thus, your answer.
you have:
1.) x-3y when x=-4 and y=9
-->>> (plug it in)
-4-3(9)
-4-27
-31
2.) a-|b| when a=-7.6 and b=-8.9
-->>>(plug it in)
-7.6-|-8.9|
-16.5
3.) 3(8x-y) when x=-4 and y=9
-->>(plug it in)
3(8(-4)-9)
3(-32-9)
3(-41)
-123
4.)
54
Thus, your answer.