the sum of the digits of a 2-digit number is 8. The number obtained by
interchanging the digits exceeds the given number by 18. Find the given numbers.
Answers
Let the digits at ones place be x. Then,
the digits at tens place = (8-x)
Original number = 10(8-x) + x
= 80 - 10x + x
= 80 - 9x
On interchanging the digits
new number obtained = 10x + 8-x
= 9x + 8
According to question,
New number - Original number = 18
9x + 8 - (80-9x) = 18
=> 9x + 8 - 80 + 9x = 18
=> 18x - 72 = 18
=> 18x = 18 + 72
=> 18x = 90
=> x = 90/18
=> x = 5
Hence, the digits at ones place is 5.
The digits at tens place = (8-5) = 3.
So, the original number is 35 and the new number is 53.
Step-by-step explanation:
Given
The sum of the digits of a 2 digit number is 8.
The number formed by interchanging the digits exceeds the given number by 18.
_________________________________
To Find
The given numbers.
_________________________________
Solution
Let the one's digit number be 'x' and the ten's digit be '8 - x'
Original Number → 10 (Ten's Digit) + 1 (One's Digit)
\sf \implies 10(8-x)+1(x)⟹10(8−x)+1(x)
\sf \implies 10(8) - 10(x) + x⟹10(8)−10(x)+x
\sf \implies80-10x+x⟹80−10x+x
\sf \implies80-9x⟹80−9x
After Interchanging the digits,
One's digit → 8 - x
Ten's digit → x
New Number → 10 (Ten's Digit) + 1 (One's Digit)
\sf \implies 10(x) + 1(8-x)⟹10(x)+1(8−x)
\sf \implies 10x+ 8 - x⟹10x+8−x
\sf \implies 9x + 8⟹9x+8
So, as the question states, when the digits of the original numbers are interchanged the new number exceeds by 18.
New number - Original Number = 18
Let's solve the equation step-by-step
\sf 9x + 8 -(80-9x) = 189x+8−(80−9x)=18
Step 1: Simplify the equation.
\sf \implies 9x + 8 -(80-9x) = 18⟹9x+8−(80−9x)=18
\sf \implies 9x + 8 - 80 + 9x = 18⟹9x+8−80+9x=18
Step 2: Combine Like Terms.
\sf \implies 9x + 8 - 80 + 9x = 18⟹9x+8−80+9x=18
\sf \implies (9x + 9x)+ (8 - 80) = 18⟹(9x+9x)+(8−80)=18
\sf \implies 18x-72=18⟹18x−72=18
Step 3: Add 72 to both sides of the equation.
\sf \implies 18x-72+72=18+72⟹18x−72+72=18+72
\sf \implies 18x=90⟹18x=90
Step 4: Divide 18 to both sides of the equation.
18x/18=90/18
∴ x = 5
∴ One's digit ⇒ x = 5
∴ Ten's digit ⇒ 8 - x = 8 - 5 = 3
∴ Original number ⇒ 35
∴ New Number ⇒ 53
___________hope it helps_____________