Question

what is PEMDAS and why do we use it

Answer 1

"Please Excuse My Dear Aunt Sally". It stands for "Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction".
 we follow PEDMAS simply because that's the accepted convention, but we have the convention because it fits common cases well and makes mathematical expressions easier to read. 

I don't know exactly what answer you're looking for but that's what I got. This shouldn't have been hard to pick up on in class lol.

Answer 2

What is PEMDAS you ask right?well PEMDAS is a thing you use to solve equations with either parentesis,exponets,when adding,subtracting,multiplying,and dividing.for example, (4+9)20÷5.the first thing that you'll do is what is in the parentesis.4+9=13.then,20÷5=4.finally since there isnt a sign on what to do with 13 &4 you just multiply.4×13=52.we use PEMDAS so it can add order when solving a problem like the example.