Math Problem Statement

A number consists of 2 digits. The digit in the Tens place exceeds the Units digit by 5. If 5 times the sum of the digits is subtracted from the number, the digits of the number are reversed. Find the number.

Solution

The problem written in the image states:

"A number consists of 2 digits. The digit in the 'Tens' place exceeds the 'Units' digit by 5. If 5 times the sum of the digits is subtracted from the number, the digits of the number are reversed. Find the number."

Let the number be 10x+y10x + y, where:

  • xx is the digit in the Tens place
  • yy is the digit in the Units place

Step 1: Define the relationship between digits.

From the problem, the Tens digit exceeds the Units digit by 5: x = y + 5 \tag{1}

Step 2: Define the condition for the reversed number.

If 5 times the sum of the digits is subtracted from the original number, the digits of the number are reversed: (10x + y) - 5(x + y) = 10y + x \tag{2}

Step 3: Solve the system of equations.

Substitute x=y+5x = y + 5 from equation (1) into equation (2): (10(y+5)+y)5((y+5)+y)=10y+(y+5)(10(y + 5) + y) - 5((y + 5) + y) = 10y + (y + 5) Simplify the left-hand side: (10y+50+y)5(2y+5)=10y+y+5(10y + 50 + y) - 5(2y + 5) = 10y + y + 5 (11y+50)10y25=11y+5(11y + 50) - 10y - 25 = 11y + 5 y+25=11y+5y + 25 = 11y + 5 255=11yy25 - 5 = 11y - y 20=10y20 = 10y y=2y = 2

Step 4: Find xx.

From equation (1), x=y+5x = y + 5, so: x=2+5=7x = 2 + 5 = 7

Thus, the original number is 10x+y=10(7)+2=7210x + y = 10(7) + 2 = 72.

Final Answer:

The number is 72.


Would you like further explanation or have any other questions?

Related Questions:

  1. How would the process change if the condition were different, such as if the difference between the digits was 4?
  2. What if the subtraction condition involved multiplying the digits instead of summing them?
  3. How would we solve this if the number had three digits instead of two?
  4. Can you explain how reversing a three-digit number would affect the equation?
  5. What mathematical strategies can be applied to solve similar digit-reversal problems?

Tip:

Always set up the problem with clear variables and ensure that all conditions are reflected in your equations. This will help avoid mistakes in complex word problems.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Number Properties

Formulas

x = y + 5 (Tens digit exceeds Units digit by 5)
(10x + y) - 5(x + y) = 10y + x (Equation representing the reversal of digits after subtraction)

Theorems

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Suitable Grade Level

Grades 6-8