Can someone please explain this question to me?

Can someone please explain this question to me? I don’t understand at all what its asking.

For each of the following values for the MPC, determine the size of the simple spending multiplier and the total change in the real GDP demand following $10 billion decrease in spending: 

A) MPC= 0.9

B) MPC= 0.75

C) MPC= 0.6