Let:
Yx = Profit from selling vitamin X
Yy = Profit from selling vitamin Y
x = Number of bottles
Those profits are given by:
[tex]\begin{gathered} Yx=5x \\ Yy=6x \end{gathered}[/tex]Therefore, for a profit of at least 42.00:
[tex]\begin{gathered} Yx+Yy\ge42.00 \\ 5x+6x\ge42 \end{gathered}[/tex]Let's check every option:
A.
[tex]\begin{gathered} 5(5)+6(2)\ge42 \\ 37\ge42 \\ _{\text{ }}False \end{gathered}[/tex]This is not a valid option.
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B.
[tex]\begin{gathered} 5(1)+6(5)\ge42 \\ 35\ge42 \\ _{\text{ }}False \end{gathered}[/tex]This is not a valid option
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C.
[tex]\begin{gathered} 5(4)+6(4)\ge42 \\ 44\ge42 \\ _{\text{ }}True \end{gathered}[/tex]This is a valid option:
Answer:
C. 4 bottles of X and 4 bottles of Y