7-3=4
9-2=7
4x7=28
Use PEMDAS for order of operations, it will save your life
Parenthesis Exponents Multiply Divide Add Subtract
Multiply and Divide and Add and Subtract can be switched around with each other, but multiply and divide always happens before add and subtract. The reason you add first here is because it is in the parenthesis.
Step-by-step explanation:

First remember that sum means to add. now think about the equation. we need to find 3 numbers that equal 159 when added together. And they are all consecutive odd numbers. so let's call the first number X. the second number would be X+2 since we have to jump over 1 even number. The third number would be X+4 since we have to jump over 2 even numbers. so now an equation to represent this would be X+(X+2)+(X+4)=159. Add like terms, and remember order of operations. if you need help getting the answers leave me a comment.
Answer:
Page number 27 is the one whose order has not changed
Step-by-step explanation:
Answer:
78%
Step-by-step explanation:
Ok to solve this we can write this as
80 = 
We put the equation like this because were finding out how much he needs to get on his 5th test x in order to get a 80%
Your grade is the average of all of your scores hence the divided by 5
We next multiply both sides of the equation by 5 to get
400 = 72+82+85+83+x
400= 322+ x
78 = x
He must get a 78% minimum on his next test to get 80%
Hope that helps!