(-.005t^3 + .1t^2 - .3t +3) - (-.004t^3 + .13^2 - .7t +2) since this is a subtraction problem you need to distribute the subtraction sign to the second problem before simplifying
so it becomes ( .004t^3 - .13t^2m+ .7t -2) now you can combine things that are alike by grouping
