Question 567094
Let {{{ x }}} = Jon's age now
{{{ x + 7 }}} = Jon's age 7 yrs from now
{{{ x + 11 }}} = Jon's age 11 yrs from now
{{{ x + 5 }}} = Jon's age 5 yrs from now
given:
{{{ 7*( x + 7 ) + 11*( x + 11 ) = 20x }}}
{{{ 7x + 49 + 11x + 121 = 20x }}}
{{{ 18x + 170 = 20x }}}
{{{ 2x = 170 }}}
{{{ x = 85 }}}
{{{ x + 5 = 90 }}}
In 5 yrs I will be 90
check:
{{{ 7*( 85 + 7 ) + 11*( 85 + 11 ) = 20*85 }}}
{{{ 7*85 + 49 + 11*85 + 121 = 20*85 }}}
{{{ 20*85 - 18*85 = 121 + 49 }}}
{{{ 2*85 = 170 }}}
{{{ 170 = 170 }}}
OK