A bag contains 50 marbles. Marsha chooses a marble, records its color, and then puts the marble back into the bag. Marsha repeats this process and records 7 red marbles and 3 yellow marbles. What is the ratio of the number of red marbles to the number of yellow marbles she chooses?

he used the algebra tiles correctly.

step-by-step explanation:

given : 3x(2x-1)

solution :

since he used algebra tiles .

armando's solution is the same in the solution shown in figure

as he distributed 2x into x and x and wrote them vertically

and also write   -1 vertically

and 3x into x and x and x and wrote it horizontally

performing the multiplication in the algebra tiles we get

and solving the given expression :

3x(2x-1)

since solving the expression using tiles   and solving the expression algebraically we get the same answer

thus   we can choose the first statement as the answer to this problem which is "he used the algebra tiles correctly".

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step-by-step explanation: