Question 88159
Let the number be written as xy where x is the number of tens and y is the number of units.


Mathematically, the number is 10x+y


So, {{{ x-y = 2 }}} --1
and {{{ x+y = (1/7)(10x+y) }}} --2


Simplifying eq2:
{{{ 7(x+y) = 10x+y }}}
{{{ 7x+7y = 10x+y }}}
{{{ 6y = 3x }}}
or {{{ 2y = x }}}


--1 is {{{ x-y = 2 }}} which then becomes {{{ 2y-y = 2 }}}
{{{ y = 2 }}}


so using {{{ 2y = x }}} and knowing that y=2, we get x=4


--> number is 42



cheers
Jon.