Please help I will give

ok so the easy way is this

Marc says he will have 20 if he doubles his cards.

if u divide 20 by 2 = 10

but His friend gave him 3 cards before.which means that

10-3 = 7

He started with 7 cards

I answered b and c.

7

Step-by-step explanation:

In the end if his cards are doubled to 20 then 20 / 2 = 10 and if his friend gave him 3 more cards then you would subtract 3 from 10 then that would = 7

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".