Answer:
2.1
Step-by-step explanation:
when you combine like terms you have to combine the d's with the d's and the nonvariable number with the nonvariable number.
this is how it should look like
(-2.8d+2.8d)+(3.4+(-1.3))
a negitive plus a posative cancel out so the d's disapier and now you only have 3.4+-1.3. this is just like subtracting so you can put it like this
3.4-1.3 and you will get 2.1
