Question 572722
Let {{{ a }}} = my age now
Let {{{ b }}} = my Daughter's age now
{{{ a - 7 }}} = my age 7 yrs ago
{{{ b - 7 }}} = my Daughter's age 7 yrs ago
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(1) {{{ a - 7 = 11*( b - 7 ) }}}
(2) {{{ a = 4b }}}
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Substitute (2) into (1)
(1) {{{ 4b - 7 = 11*( b - 7 ) }}}
(1) {{{ 4b - 7 = 11b - 77 }}}
(1) {{{ 7b = 70 }}}
(1) {{{ b = 10 }}}
and
(2) {{{ a = 4b }}}
(2) {{{ a = 4*10 }}}
(2) {{{ a = 40 }}}
My age is 40
check answer:
(1) {{{ a - 7 = 11*( b - 7 ) }}}
(1) {{{ 40 - 7 = 11*( 10 - 7 ) }}}
(1) {{{ 33 = 11*3 }}}
(1) {{{ 33 = 33 }}}
OK