Mary is twice as old as Elizabeth. John is two years older than Elizabeth. John's and Elizabeth's ages combined equal eight. How old is Mary? Explain your reasoning.
Let's call Elizabeth's age x. We know that John is two years older than Elizabeth, and their combined ages are 8. So x + x + 2 = 8, meaning Elizabeth is 3. Mary is twice Elizabeth's age, which makes Mary 6.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: Mary is twice as old as Elizabeth. John is two years older than Elizabeth. John's and Elizabeth's ages combined equal eight. How old is Mary? Explain your reasoning.
### Input: 
### Response: Let's call Elizabeth's age x. We know that John is two years older than Elizabeth, and their combined ages are 8. So x + x + 2 = 8, meaning Elizabeth is 3. Mary is twice Elizabeth's age, which makes Mary 6.