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

### Instruction:
Karina was born in 1970 and she is currently twice as old as her brother. If her current age is 40, in what year was her brother born?

### Response:
 Ikiwa Karina kwa sasa ana miaka 40, na yeye ni mara mbili ya umri wa mdogo wake, basi mdogo wake kwa sasa ana miaka 40/2 = <<40/2=20>>20.
Ikiwa Karina alizaliwa mwaka 1970, basi mdogo wake alizaliwa mwaka 1970+20 = <<1990=1990>>1990.