A teacher wanted to determine the effectiveness of two different learning tools—a computer program or a hands-on approach—for a particular concept she was preparing to teach. She will assign her students to one of the two methods to spend the whole class time to learn this concept. Which of the following variables would be moderated due to random assignment?

A. the teacher
B. time spent in class
C. computer experience
D. the different learning tools

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".

8 2/3 is the answer

step-by-step explanation: just use a calculator

answer is x<