Answer:
The present age of Sam is 20 years .
Step-by-step explanation:
Given as :
Let The age of John = J years
Let The age of Sam = S years
∵ Sam is 12 years older than John
so, The age of Sam = 12 + The age of John
i.e S = 12 + J .....1
<u>Again</u>
Before 5 years ago
The age of Sam = 5 times age of John
So, (S - 5) = 5 × (J - 5)
Or, S - 5 = 5 J - 25
Or, 5 J - S = 25 - 5
Or, 5 J - S = 20 .........2
Solving eq 1 and eq 2
[5 J - (12 + J)] = 20
Or, 5 J - 12 - J = 20
Or, 4 J = 20 + 12
Or, 4 J = 32
∴ J = 
i.e J = 8 years
So, The age of John = J = 8 years
Put The value of J into eq 1
∵ S = 12 + J
So, S = 12 + 8
i.e S = 20 years
So, The present age of Sam = S = 20 years .
Hence, The present age of Sam is 20 years . Answer
C. The Tetrahhedron has 4 faces, all of which are triangles. It also has four vertices and six edges.
Complete question :
Mr. Nelson lost one of his students' test papers. He knows that the other 4 students scored as follows: 60, 62, 56, 57. He also knows that the average score is 59.2. What is the score on the missing paper?
Answer:
61
Step-by-step explanation:
Given the following :
Total number of students = 4 + 1 missing = 5
Score on the four avaliable papers = 60, 62, 56, 57
Average score of the 5 papers = 59.2
Score on missing paper :
Sum of each score / number of papers
Sum of each score = sum of available scores + missing score
Let missing score = m
(60 + 62 + 56 + 57 + m) = 235 + m
Recall:
Average = total sum / number of observations
Hence,
59.2 = (235 + m) / 5
59.2 × 5 = 235 + m
296 = 235 + m
m = 296 - 235
m = 61
Missing score = 61
You would use the distributive property with the negative. So the second x becomes negative, but since the 7 is already negative it becomes positive. Think of it as if you put the two dashes together you can make a plus sign.
