Answer: 10.764 pounds
Step-by-step explanation: 0.38 is the equivalence 38% 
-  First, You need to multiply 7.8 by 0.38 because if do that you will get 38% of the carton's weight (no matter how many zeros you put at the end of a decimal number it's still the same number.)  7.8 x 0.38 2.964
 -  Now, you have the initial weight, 7.8 (Which is equal to 100%) to the new number, 2.964 (which is 38%) and add them together  7.8 + 2.964= 10.764 (100%+ 38%= 138% mind blown)
 - Dont forget Labels  which makes it 10.764 pounds