HELP with these two.

42d = -252 (since 42 is multiplied by d, you have to divide by 42 on both sides to get what d is)

d= -6

20 = n / (-4) (since n is being divided by -4, you have to multiply by -4 on both sides to get what n is)

n= -80

Step-by-step explanation:

to get what the variable is, you have to "undo" the operation that is being done.

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".

step-by-step explanation:

sry but any answer choices