Draw and label an example of a right triangle, an acute triangle, and an obtuse triangle.

The draw in the attached figure

Step-by-step explanation:

1) A right triangle  is a triangle that has one right interior angle

see the attached triangle ABC to better understand the problem

2) An acute triangle , is a triangle that has the three interior angles less than 90 degrees

see the attached triangle DEF to better understand the problem

3) An obtuse triangle , is a triangle that has one interior angle greater than 90 degrees

see the attached triangle XYZ to better understand the problem    

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".