Question

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

Answer 1

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`