Hi there!
Let the Original number be 10x + y.
Then,
• Ten's digit = x.
• Unit's digit = y.
According to th' Question :-
⇒x - 7 = y
⇒x - y = 7 ---(i)
And,
⇒10x + y = 10 (x + y)
⇒10x + y = 10x + 10y
⇒10x - 10x = 10y - y
⇒9y = 0
⇒y = 0
Substitute th' value of ' y ' in Eqn. (i)
⇒x - y = 7
⇒x - 0 = 7
⇒x = 7
∴ Original number = 10x + y = 10 × 7 + 0 = 70
Hence,
The required two digit number is 70
~ Hope it helps!
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