Question 1144969
Let {{{x}}} be the unknown number

Let {{{x/7}}} be the unknown number divided by {{{7}}}

Let {{{ x - 12 }}} be the unknown number decreased by {{{12}}}

Set the expressions equal to each other

{{{x/7 = (x-12)}}}

Convert the right side to a fraction by placing it over {{{1}}}

{{{x/7 = (x-12)/1}}}

Cross multiply to get 

{{{ 7(x-12) = x * 1 }}}

Simplify by distributing the {{{7}}}

{{{ x(7) - 12(7) = x * 1 }}}

Simplify by multiplying

{{{ 7x - 84 = x}}}

Combine like terms by subtracting {{{7x}}} from both sides

{{{ 7x - 7x - 84 = x - 7x}}}

Simplify

{{{ 0 = 84 = -6x}}}

Simplify 

{{{ -84 = -6x }}}

Isolate {{{x}}} by dividing by sides by {{{-6}}}

{{{ (-84)/(-6) = (-6x)/(-6)}}}

Simplify, remember that a negative by a negative is a positive

{{{ 14 = x }}}

Check:

{{{x/7 = (x-12)}}}

Substitute in the {{{ 14 }}}

{{{ 14/7 = (14-12)}}}

Evaluate

{{{ 2 = 2}}}

Correct!