Hey!
Since it says "all together", that means you have to add both amounts.
In one bucket, she had 4.6 gallons, and in another, she had 2.3 gallons. Add 4.6 and 2.3
[tex] 4.6 + 2.3 = 6.9 [/tex]
[tex] \framebox{She had 6.9 gallons of water altogether} [/tex]