A number of two digits is such that twice the tense digit is 8 less than seven times the unit digit,when the digits is reversed,the numbers are increased by 9.what are the numbers?
tens' digit, not tense digit ...
so, we have
t = 7u-8
10u+t = 10t+u + 9
recall that if reversing the digits increases the number by 9, the two digits are consecutive numbers.