Carina is 5 year older than Marnie. Three years ago, she was twice as old as Marnie. how old are they now?

1 Answer
Jun 24, 2018

Answer:

Marnie is 2 years old and Carina is 7 years old.

Explanation:

To solve our problem, let's write our information as equations. Carina is 5 years older than Marnie. Let Carnie be #c# and Marnie be #m#. Our equation would be #c=m+5#. Three years ago (#c-3#), Carina was twice as old as Marnie (#2m#). So, #c-3=2m#.

#c=m+5#
#c-3=2m#

After this, we can substitute #c# in the second equation for our entire first equation:

#m+5-3=2m#
#m+2=2m#
#2=m#

Next, let's put #2# into our first equation:

#c=2+5#
#c=7#

#m=2, c=7#