Answer:
Step-by-step explanation:
![\frac{2x}{a}+\frac{y}{b}=2 ---------(i)\\\\\frac{x}{a}-\frac{y}{b}=4-------------(ii)\\\\](https://tex.z-dn.net/?f=%5Cfrac%7B2x%7D%7Ba%7D%2B%5Cfrac%7By%7D%7Bb%7D%3D2%20---------%28i%29%5C%5C%5C%5C%5Cfrac%7Bx%7D%7Ba%7D-%5Cfrac%7By%7D%7Bb%7D%3D4-------------%28ii%29%5C%5C%5C%5C)
Add the equations. So, y/b will be eliminated.
![\frac{3x}{a}=6\\\\x=6*\frac{a}{3}\\\\x=2a\\\\](https://tex.z-dn.net/?f=%5Cfrac%7B3x%7D%7Ba%7D%3D6%5C%5C%5C%5Cx%3D6%2A%5Cfrac%7Ba%7D%7B3%7D%5C%5C%5C%5Cx%3D2a%5C%5C%5C%5C)
x= 2a
Substitute x = 2a in equation((i)
![\frac{2*2a}{a}+\frac{y}{b}=2\\\\4+\frac{y}{b}=2\\\\\frac{y}{b}=2-4\\\\\frac{y}{b}=-2\\\\y=-2b](https://tex.z-dn.net/?f=%5Cfrac%7B2%2A2a%7D%7Ba%7D%2B%5Cfrac%7By%7D%7Bb%7D%3D2%5C%5C%5C%5C4%2B%5Cfrac%7By%7D%7Bb%7D%3D2%5C%5C%5C%5C%5Cfrac%7By%7D%7Bb%7D%3D2-4%5C%5C%5C%5C%5Cfrac%7By%7D%7Bb%7D%3D-2%5C%5C%5C%5Cy%3D-2b)
y = - 2b
5 is not a divisor of any of the dimensions of the given box, so selections A, C, D can't work.
Each of the dimensions of selection B is a divisor of a different dimension of the box, so ...
.. the correct choice is selection B) 7 × 9 × 12.
Ritin has 21/5 lemonade and he distributed meaning he took away 13/4 liters of lemonade. Find a common denominator between 5 and 4. Since we know 5 times 4 is 20 the smallest common denominator so lets multiply 21/5 by 4 getting 84/20 and multiply 13/4 by 5 getting 65/20. Since both fractions have 20 as the denominator, subtract 84/20 by 65/20 and you get 19/20 liters of lemonade as your answer.
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Answer is 19/20 liters of lemonade Ritin has left