Answer:
Step-by-step explanation:
3y + 39 = 33
3y = -6
y = -2
1/4(-2)= -2/4 = -1/2
y=mx+b
Answer: 28
the cost of 7 diaries is 28
First you have to find out the cost of one diary by dividing 12 by 3, that will give us 4, and then the last step is multiplying 4 by 7.
![\left[\begin{array}{ccc}1&2&3\\4&5&6\\7&8&9\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%262%263%5C%5C4%265%266%5C%5C7%268%269%5Cend%7Barray%7D%5Cright%5D%20)