Question 1045130
Let {{{ a }}} = Susidu's age in 2005
Let {{{ b }}} = Sasidu's age in 2005
{{{ a + 5 }}} = Susidu's age in 2010
{{{ b + 5 }}} = Sasidu's age in 2010
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(1) {{{ a = 3b }}}
(2) {{{ a + 5 = b + 5 + 30 }}}
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(2) {{{ a + 5 = b + 35 }}}
(2) {{{ a - b = 30 }}}
Substitute (1) into (2)
(2) {{{ 3b - b = 30 }}}
(2) {{{ 2b = 30 }}}
(2) {{{ b = 15 }}}
and
(1) {{{ a = 3b }}}
(1) {{{ a = 3*15 }}}
(1) {{{ a = 45 }}}
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45 = Susidu's age in 2005
15 = Sasidu's age in 2005
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In what year is Susidu's age double Sasidu's?
Let {{{ x }}} = the number of years after 2005
that is true
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{{{ a + x  = 2*( b + x ) }}}
{{{ 45 + x = 2*( 15 + x ) }}}
{{{ 45 + x = 30 + 2x }}}
{{{ x = 15 }}}
2005 + 15 = 2020
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In 2020, Susidu's age is double Sasidu's
check:
{{{ a + 15 = 45 + 15 }}}
{{{ a + 15 = 60 }}}
and
{{{ b + 15 = 15 + 15 }}}
{{{ b + 15 = 30 }}}
and
{{{ 60 = 2*30 }}}
OK