Hey there!
Let's combine like terms!
First, let's write them together, like so:
-2.8d+2.8d-2.8d+2.8d-1.33+3.4-1.33
And now we can see that -2.8d and 2.8d cancel out:
-2.8d+2.8d-1.33+3.4-1.33
And they cancel out again:
-1.3+3.4-1.33
Now all we have to do is add the numbers together:
0.77
Hope it helps!