Answer:
2 
Step-by-step explanation:
The question state that; the sum of a number, 1/6 of that number, 2 1/2 of that number, and 7 is 12 1/2. Find the number.
First, we need to interpret and represent this statement mathematically
Let n be the number.
The sum means 'addition'
1/6 of that number is 1/6 of n = 1/6 × n = 
2 1/2 of that number is 2 1/2 of n = 2 1/2 × n = 5/2 × n = 
So the question says that, when we add;
,
and 7 all together, the value is 12 1/2
That is;
+
+ 7 = 12 1/2
+
+ 7 =
( changing 12 1/2 to improper fraction will give
)
So we can now go ahead and solve for n
+
+ 7 =
subtract 7 from both-side of the equation
+
=
- 7
= 
= 
can be reduced to give us 
= 
Cross multiply
8n × 2 = 11× 3
16n = 33
Divide both-side of the equation by 16
= 
(On the left-hand side of the equation, 16 will cancel-out 16 leaving us with just, while on the right-hand side of the equation 33 will be divided by 16)
n =
= 
Therefore the number is 