The change in period-to-period operating income when using variable costing can be explained by the change in the

Unit sales level multiplied by a constant unit contribution margin.

Explanation:

The change in period-to-period operating income when using variable costing can be explained by the change in the Unit sales level multiplied by a constant unit contribution margin.

Hope this helps!

answer; ///(c) i believe its it ignores cash flows following the payback period;

if i need to borrow money for anything, it would be for something like a house or an apartment but, that depend on the situation.

is this good enough?