Answer:
Step-by-step explanation:
Show that if 3x – 7 = 5, then x = 4.
Here, our given statement is 3x – 7 = 5, and we're asked to prove x = 4.
x=4
Statements	Reasons
1. 3x – 7 = 5	Given
2. 3x – 7 + 7 = 5 + 7	Addition of 7 to equation (1)
3. 3x + 0 = 5 + 7	Substitution of –7 + 7 = 0 into (2)
4. 3x = 5 + 7	Substitution of 3x + 0 = 3x into (3)
5. 3x = 12	Substitution of 5 + 7 = 12 into (4)
6. 3x⁄3 = 12⁄3	Dividing equation (5) by 3
7. x = 12⁄3	Substitution of 3x⁄3 = x into (6)
8. x = 4	Substitution of 12⁄3 = 4 into (7)
Is there such a thing as being too descriptive? Yep, and that was it, since over half the proof was devoted to telling the reader how to do arithmetic. We'll typically take numerical computation for granted, and write proofs like this:
 
        
             
        
        
        
Answer: 330
Step-by-step explanation:
 
        
             
        
        
        
K= 8. If you look at the pattern each x value is multiplied by 8 to give you the y value. You could also solve it by:
40=k5
40/5=k
8=k
you could do this with any of the x or y values and still end up with 8.
        
             
        
        
        
You would just do 13+15+26+32 which would equal 86mm