Ashirt cost $18.99. pants cost $29.50. a jacket costs $55.99. how much more did the jacket cost than the pants and shirt put together?

I'm pretty sure that the answer would be 7.50 because if you do ($18.99+$29.50)x2, you would get $7.50.

$29.50 + $18.99=  48.49
That would be the pants and shirt.

Then do 55.99 - 48.49. 
That would bring you to a grand total of $7.50
So, the jacket would be 7.50 more than the pants and shirt combined.

                                  Hope this helps.
                                 Sincerely, HodctIlana