Kristina, Liz, and Heather all made cookies. Kristina made 1.8 dozen less than 6 times as many dozen as Heather. Liz made 2.7 dozen more than 5 times as many dozen as Heather. If Kristina and Liz made the same number of cookies, how many dozen cookies did Heather make?

Based on the number of cookies each girl made and if Kristina and Liz made the same number of cookies, then Heather made 4.2 dozen cookies.

Step-by-step explanation:

In order to find the number of cookies that Heather made, you need to set up two equations that represent the number of cookies that Kristina and Liz each made.  Since Kristina made 2.4 dozen less than 6 times as many dozen as Heather, we can represent that with the equation  6c - 2.4.  Since Liz made 1.8 dozen more than 5 times as many dozen as Heather, we can represent that with the equation 5c + 1.8.  We can set both equations equal to each other since Liz and Kristina made the same number, so 6c - 2.4 = 5c + 1.8.  Solving for 'c', which represents how many dozen cookies Heather made, we get 4.2  

it would be:

c.parallelogram.