The tens digit of a two-digit number is 4 more than the units digit. The number is 7 less than 8 times the sum of the digits. Find the number.

Question

Please show how to set up the problem to solve it.  Thank you for the help!

Answer 1

ab represents the number (ab means 10a+b)

a=b+4

10a+b=8(a+b)-7

10a+b=8a+8b-7

10a+b-8a-8b=-7

2a-7b=-7

from a=b+4, substitute...

2(b+4)-7b=-7

2b+8-7b=-7

-5b+8=-7

-5b=-8-7

-5b=-15

5b=15

b=15/5

b=3

a=b+4

a=3+4

a=7

73 is the number