6. A two-digit number is such that the sum of the ones and the tens digit is ten. If the digits are reversed, the new number formed exceeds the original number by 54. Find the number. (3 marks)

7. Solve the following simultaneous equations by the elimination method. (3 marks)



Answer :

Alright, let's tackle the problem step-by-step.

### Problem Statement:
A two-digit number has the sum of its ones and tens digit equal to ten. If the digits of the number are reversed, it forms a new number that exceeds the original number by 54. We need to find this two-digit number.

### Step-by-Step Solution:

1. Set Up Variables:
- Let [tex]\( x \)[/tex] be the tens digit of the original number.
- Let [tex]\( y \)[/tex] be the ones digit of the original number.

2. Formulate Equations:
- According to the problem, the sum of the tens and ones digit is 10:
[tex]\[ x + y = 10 \][/tex]
- When the digits are reversed, the new number formed exceeds the original number by 54. The original number is [tex]\( 10x + y \)[/tex] and the new number is [tex]\( 10y + x \)[/tex]. This gives us:
[tex]\[ (10y + x) = (10x + y) + 54 \][/tex]

3. Simplify the Second Equation:
- Rearrange the second equation:
[tex]\[ 10y + x - y - 10x = 54 \][/tex]
- Combine like terms:
[tex]\[ 9y - 9x = 54 \][/tex]
- Simplify by dividing both sides by 9:
[tex]\[ y - x = 6 \][/tex]

4. Solve the System of Equations:
- Now we have two equations:
[tex]\[ 1) \quad x + y = 10 \][/tex]
[tex]\[ 2) \quad y - x = 6 \][/tex]

To solve these equations, we can add them together to eliminate [tex]\( x \)[/tex]:

[tex]\[ (x + y) + (y - x) = 10 + 6 \][/tex]
[tex]\[ x + y + y - x = 16 \][/tex]
[tex]\[ 2y = 16 \][/tex]
[tex]\[ y = 8 \][/tex]

- Substitute [tex]\( y = 8 \)[/tex] back into the first equation:
[tex]\[ x + 8 = 10 \][/tex]
[tex]\[ x = 2 \][/tex]

5. Form the Original Number:
- The original number is formed as [tex]\( 10x + y \)[/tex]:
[tex]\[ 10 \cdot 2 + 8 = 28 \][/tex]

### Conclusion:
The original two-digit number is:
[tex]\[ \boxed{28} \][/tex]