The tens digit of a two-digit number is five more than the units digit. Seven times the sum of the digits of this number is 3 less than the number itself. Find the number.

43

Step-by-step 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

you never say the total so we cant find the percentage used for petrol

step-by-step explanation: