<|im_start|>system
You are a helpful assistant. You first thinks about the reasoning process in the mind and then provides the user with the answer.<|im_end|>
<|im_start|>user
Challenge yourself to get a total of 135 using only the numbers 10, 20, 30, and 40. Use basic arithmetic operations (+, -, *, /) and each number once. Show your work in <think> </think> tags. Your final answer should be presented in <answer> </answer> tags, following the example provided. Similar to <answer> (10 + 20) * 3 = 90, then 90 + 15 = 105, finally 135 - 15 = 120</answer>.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>