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

### Instruction:
The difference in age between Declan's elder son and younger son is 10 years. If the elder son is 40 years old now, how old will the younger son be 30 years from now?

### Response:
If the elder son is 40 years old, the younger son is 40-10 = <<40-10=30>>30 years old.
In 30 years from now, the younger son will be 30+30 = <<30+30=60>>60 years old.
#### 60