A 20% acid solution is mixed with a 70% acid solution to get 100 liters of a 50% solution. If x= the amount of 20% solution and y = the amount of 70% solution, which of the following expressions equals 500?
0.2x+0.7y
20x + 70y
2x+7y

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The seventh-grade students at charleston middle school are choosing one girl and one boy for student council. their choices for girls are michaela (m), candice (c), and raven (r), and for boys, neil (n), barney (b), and ted (t). the sample space for the combined selection is represented in the table. complete the table and the sentence beneath it.

Astandard doorway measures 6 feet 8 inches by 3 feet. what is the largest dimension that will fit through the doorway without bending?