Question 829765


Carol is {{{15}}} years {{{older}}} than her sister Amanda;


{{{Carol=Amanda +15}}}......eq.1

Mike is two times as old as Amanda.


{{{Mike=2*Amanda}}}............eq.2

the sum of their ages is {{{35}}}:

{{{Carol+ Amanda+ Mike=35}}}.............eq.3....substitute {{{Carol}}} from eq.1 and {{{Mike}}} from eq.2


{{{Amanda +15+ Amanda+ 2*Amanda=35}}} .............solve for {{{Amanda}}}


{{{ 4*Amanda=35-15}}}

{{{ 4*Amanda=20}}}

{{{ Amanda=20/4}}}

{{{ highlight(Amanda=5)}}}


 How old is carol? go to {{{Carol=Amanda +15}}}......eq.1 plug in {{{ highlight(Amanda=5)}}}

{{{Carol=5 +15}}}

{{{highlight(Carol=20)}}}

and go to {{{Mike=2*Amanda}}} ............eq.2  plug in {{{ highlight(Amanda=5)}}}

 {{{Mike=2*5}}}

{{{highlight(Mike=10)}}}