Answer:
The sum of ages of all 18 pupils in the class = 81
Step-by-step explanation:
Total number of pupil in the class = 18
Average of years in the class = 
Now, 
⇒Average of sum of ages in the class = 4.05
Let us assume the sum of ages of all students in the class = m
By the formula for AVERAGE:


or, m = 18 x 4.5 = 81
Hence, the sum of ages of all 18 pupils in the class = 81
Answer:
48.
or 
51.
or 
54.
or 
57.
or 
Step-by-step explanation:
48. 
-There are two equations:
Equation 1:

or
Equation 2:

Solving equation 1:




(Inequality sign changed, because of dividing by a negative number)
-Solving equation 2:




(Inequality sign changed, because of dividing by a negative number)
-Answers:
or 
51. 
-There are two equations:
Equation 1:

or
Equation 2:

-Solving equation 1:



-Solving equation 2:



Answers:
or 
54. 
-There are two equations:
Equation 1:

or
Equation 2:

-Solving equation 1:





-Solving equation 2:





-Answers:
or 
57. 
-There are two equations:
Equation 1:

or
Equation 2:

-Solving equation 1:





Solving equation 2:





Answers:
or 
And we are finished.
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Answer:
Infinity
Step-by-step explanation:
4,6 and 4,10
10 - 6=4
4 - 4=0
4 divided by 0 = Infinity
What equations? I see no equations. Do you have a picture, if take a picture