"Published in Daly City, California, USA"
The sum of the digits of a two-digit number is 7. When the digits are reversed, the number is increased by 27. Find the number.
Solution:
From the description of a given word problem, it is an application of linear equation with two equations, two unknowns.
Let x = be the value of one's digit
y = be the value of ten's digit
From the statement "The sum of the digits of a two-digit number is 7.", then the working equation is
From the statement "When the digits are reversed, the number is increased by 27.", then the working equation is
Hence, the working equations for the given problem are
If you add the two working equation, y will be cancelled and the value of x which is the one's digit is
Substitute the value of x to any of the working equations. The value of y which is the ten's digit is
Therefore, the value of a two-digit number is 25.
Check:
