<|im_start|>system
You are a helpful assistant. You first think about the reasoning process in the mind and then provide the user with the answer. You should try to truely solve the question by yourself without cheating.  <|im_end|>
<|im_start|>user
 Given a geometric series {a_n} where the sum of the first n terms is denoted by S_n, and given that S_{10} = 10 and S_{30} = 70, calculate the value of S_{40}. Express your answer as a single numerical value. Show your work in <think> </think> tags. And return the final answer in <answer> </answer> tags.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>
user
150
Given a geometric series {a_n} where the sum of the first n terms is denoted by S_n, and given that S_{10} = 10 and S_{30} = 70, calculate the value of S_{40}. Express your answer as a single numerical value.
test