Human: Christian is twice as old as Brian. In eight more years, Brian will be 40 years old. How old will Christian be in eight years? Assistant:
If in eight years Brian will be 40 years old, he is currently 40-8 = 32 years old.
Since Christian is twice as old as Brian, he is 2*32 = 64 years old.
In 8 years, Christian will be 64+8 = 72 years old.