Question 706405
Let t = the count of the tens
Let u = the count of the ones or units.


In expanded form, the two digit number is 10t+u.


Translation from written English into arithmetic symbolism:
{{{10t+u=7+6(t+u)}}} AND {{{u=-3+10t}}}


Transforming those equations should give the system:
{{{4t-5u=7}}}
{{{10t-u=3}}}
Be-aware, I may have made a mistake in there.  Try approach described on your own, see if you get a good result.