Answer:
There are 35 students in his class.
Step-by-step explanation:
1. Create a proportion: 60/100=21/x
2. Cross multiply, or not (I prefer to cross multiply). 60x=2100
3. Solve the equation: x=35.
Answer: There are 35 students in his class, 14 people going in school, 21 student online.
After clarification we see the respective diameters are


We're asked about the ratio

Now we can go through the choices.
A. If a = 4 and b = 6, then cell a is 100 times greater than cell b.

It would be more proper to say the diameter of cell A is 100 times the diameter of cell B, but yes, this is TRUE.
B. If a = 4 and b = 6, then cell b is 100 times greater than cell a.
FALSE. 10 to the minus 4 is 100 times bigger than 10 to the minus 6, so a is bigger.
C. If a = 4 and b = 6, then cell a is 2 times greater than cell b.
FALSE. We already calculated its 100 times bigger.
D. If a = 4 and b = 6, then cell b is 2 times greater than cell a.
FALSE.
The sum of two consecutive even integers is a+(a+2) and divided by four is
(a+(a+2))/4 = 189.5
(2a+2)/4 = 189.5
2a+2 = 189.5 * 4
2a+2 = 758
2a = 758 - 2
2a = 756
a = 756/2 = 378
first number is a = 378
second number is a+2 = 378+2 = 380
ANSWER
Find out the how old was we when he died.
To proof
Let us assume that the age of the Adam be x
As given
Adam lived a quarter of his life as a boy as fifth as a young man, a third in middle-age and 13 years in retirement.

L.C.M of denominator i.e ( 4,5,3) =60
than the equation becomes
60x = 15x + 12x +20x +780
60x - 47x = 780
13x = 780

x = 60 years
therefore the Adam age when he died is 60 years.
Hence proved