so the container was 2/5 full, then you dump in it 6 gallons and it went up to 7/10 full.
alrite, let's say the container can hold "x" gallons.
[tex]\bf \cfrac{2}{5}x+\cfrac{7}{10}x=6\implies \cfrac{(2\cdot 2)x+7x}{10}=6\implies \cfrac{4x+7x}{10}=6
\\\\\\
\cfrac{11x}{10}=6\implies 11x=60\implies x=\cfrac{60}{11}\implies x=5\frac{5}{11}[/tex]
