Question 983103
Let {{{ a }}} = Mom's age now
Let {{{ b }}} = Meenakshi's age now
Let {{{ c }}} = Dad's age now
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given:
(1) {{{ a + b + c = 70 }}}
(2) {{{ c = 6b }}}
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The amount you add to each of their ages
when the sum of their ages is {{{ 2*70 = 140 }}}
is {{{ 70/3 = 23.333 }}}
Now I have the equation:
{{{ a + 23.333 + b + 23.333 + c + 23.333 = 70 + 70 }}}
I can now say:
{{{ b + 23.333 = (1/2)*( c + 23.333 ) }}}
Plug (2) into this equation
{{{ b + 23.333 = (1/2)*( 6b + 23.333 ) }}} 
{{{ 2b + 46.667 = 6b + 23.333 }}}
{{{ 4b = 23.333 }}}
{{{ b = 5.8333 }}}
and
(2) {{{ c = 6b }}}
(2) {{{ c = 35 }}}
and
(1) {{{ a + b + c = 70 }}}
(1) {{{ a + 5.8333 + 35 = 70 }}} 
(1) {{{ a = 70 - 40.8333 }}}
(1) {{{ a = 29.1667 }}}
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{{{ .1667*12 = 2 }}}
{{{ .8333*12 = 10 }}}
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Mom is 29 and 2 months
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check answer:
Menakshi's age is 5 yrs 10 months
Dad's age is 35
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(1) {{{ a + b + c = 70 }}}
(1) {{{ 29.1667 + 5.8333 + 35 = 70 }}}
(1) {{{ 35 + 35 = 70 }}}
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(2) {{{ c = 6b }}}
(2) {{{ 35 = 6*5.8333 }}}
(2) {{{ 35 = 35 }}}
OK