<|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
Using the numbers [4, 9, 15, 26], craft an equation that results in 21. Employ basic arithmetic operations (+, -, *, /) and prioritize leading without over-difficulty. Show your work in <think> </think> tags. And, return the final result and equation in <answer> </answer> tags, consistent with asking structure provided, accessible: <answer> (9 * 2) + 3 = 21 </answer>.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>