Question 721268
Let {{{ b }}} = Ben's age now
Let {{{ h }}} = Henry's age now
{{{ b + 13 }}} = Ben's age in 13 yrs
{{{ h + 13 }}} = Henry's age in 13 yrs
given:
(1) {{{ b = 2h + 7 }}}
(2) {{{ ( b + 13 ) + ( h + 13 ) = 78 }}}
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(2) {{{ b + h + 26 = 78 }}}
(2) {{{ b + h = 52 }}}
and
(1) {{{ b - 2h = 7 }}}
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Subtract (1) from (2)
(2) {{{ b + h = 52 }}}
(1) {{{ -b + 2h = -7 }}}
{{{ 3h = 45 }}}
{{{ h = 15 }}}
and, since
(1) {{{ b = 2h + 7 }}}
(1) {{{ b = 2*15 + 7 }}}
(1) {{{ b = 37 }}}
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Ben is 37 now
check answer:
(2) {{{ ( b + 13 ) + ( h + 13 ) = 78 }}}
(2) {{{ ( 37 + 13 ) + ( 15 + 13 ) = 78 }}}
(2) {{{ 50 + 28 = 78 }}}
(2) {{{ 78 = 78 }}}
OK