Answer:
43
Explanation:
Let
The unit digit = x
The tens digit = y
The number = 10x + y
The tens digit of a two-digit number is five more than the units digit.
y = x + 5
Seven times the sum of the digits of this number is 3 less than the number itself.
7(x + y) = 10x + y - 3
7x + 7y = 10x + y - 3
Find the number.
We substitute x + 5 for y
7x + 7(x + 5) = 10x + (x + 5) - 3
7x + 7x + 35 = 10x + x + 5x - 3
14x + 35 = 11x + 5x - 3
Collect like terms
35 + 3 = 11x + 5x -14x
38 = 16x - 14x
38 = 2x
x = 38/2
x = 19
Solving for y
y = x + 5
y = 19 + 5
y = 24
The number = 19 + 24
= 43