Answer:
Step-by-step explanation:
6x+9=63
6x=63-9
6x=54
x=54/6
x=9
I encourage you to figure out the justification yourself.
Answer:

Step-by-step explanation:
Given Data,
Q=23000 J
c=4.184 J/g °c
Δt= 68 °c
m=?
By using this equation,
Q=mcΔt

In order to have a function we can't repeat any value in the x, therefore in order to have a function represented in the table the question mark must be 2
Answer: 13 1/8
Explanation: since he cut two pieces and each piece is 4 1/4 you’re going to add 4 1/4 to 4 1/2 which makes it two pieces and the sum would be 8 1/2 then you’re going to 8 1/2 from the original length, 21 5/8 which is going to leave you with the remaining length being 13 1/8.
Hope it helps:)