Question 1104835
Let {{{ x }}} = her current age
{{{ x + 21 = 4x }}}
{{{ 3x = 21 }}}
{{{ x = 7 }}}
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Her current age is 7
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check:
{{{ x + 21  = 4x }}}
{{{ 7 + 21 = 4*7 }}}
{{{ 28 = 28 }}}
OK