Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
Isabella is twice as old as Antonio.  In 18 months, she will be 10 years old.  How many months old is Antonio?

### Response:
First, we find Isabella's age by subtracting 18 months from the number of months in 10 years, which is 120 months. We get 120-18 = <<120-18=102>>102 months.
Since Isabella is twice as old as Antonio, we divide her age by 2 to find Antonio's age, getting 102/2 = <<102/2=51>>51 months.
#### 51