Answer: 7.8
Step-by-step explanation: If we want to find the amount that was in the pitcher before then we subtract 2.6 from 10.4 to find the original amount because if the pitcher were to contain an amount that only adds up to 10.4 before we add 2.6 then the number that adds with 2.6 to equal 10.4 is our answer
hence our answer 7.8
If I pick 10, then 2(10)+13=33
If I pick 15, then 2(15)+13=43
If I pick 12, then 2(12)+13=37
