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Example of number problem solving Question 1
Question:
The sum of a number subtract itself, add itself and divide by itself is 49. What is the number?
Solution:
the number is x
the number subtract itself is: (x - x)
the number add itself is: (x + x)
the number divide itself is: x/x
given: the sum of a number subtract itself, add itself and divide by itself is 49
so we get the equation:
(x - x) + (x + x) + x/x = 49
remove parentheses
x - x + x + x + 1 = 49
keep all variables in the left side of the equation and move all numbers to the right side of the equation
2x = -1 + 49
2x = 48
x = 24
so the number is 24

This is a one variable one degree equation problem solving. The unknow number is x. The number subtract itself can be written as (x - x). The number add itself can be written as (x + x). The number divide by itself can be written as x/x. Based on the given condition, we get the equation. Note when move a number cross the equal sign, the number will change its sign which equivalent to add an item in both side of the equation. Combine similar (like) terms in left side of the equation. Divide by the coefficient in both side of the equation to get the value of the variable.