A rectangular chocolate bar is made of equal squares. Irena breaks off two complete strips of squares and eats the 12 squares she obtains. Later, Jack breaks off one complete strip of squares from the same bar and eats the 9 squares he obtains. How many squares of chocolate are left in the bar?

There are three more square chocolates left

Step-by-step explanation:

We know that Irena breaks off 2 complete strips and eats 12 meaning each strip had 6 squares. Jack breaks off 9. So if we add all the squares into rows of 6, we get four strips of chocolate from the beginning. Since Jack and Irena obtained 21 chocolate squares altogether, we have 3 chocolate squares that are remaining. I hope this helps ;)

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional