Question 1116198
Let the tens digit = {{{ t }}}
Let the units digit = {{{ u }}}
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(1) {{{ t + u = 12 }}}
(2) {{{ 10t + u - 36 = 10u + t }}}
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(2) {{{ 9t - 9u = 36 }}}
(2) {{{ t - u = 4 }}}
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Add (1) and (2)
(1) {{{ t + u = 12 }}}
(2) {{{ t - u = 4 }}}
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{{{ 2t = 16 }}}
{{{ t = 8 }}}
and
(1) {{{ 8 + u = 12 }}}
(1) {{{ u = 4 }}}
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The original number is 84
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check:
{{{ 84 - 36 = 48 }}}
The digits are reversed
OK