solution: We have $q(1) = b\cdot 1 + 1 = b+1$, so $f(q(1)) = f(b+1)$. Applying the definition of $f$, we have $f(q(1)) = f(b+1) = (b+1) - 3 = b-2$.  Therefore, the equation $f(q(1)) = -3$ gives us $b-2 = -3$, so $ b= \boxed{-1}$.
prompt.content: <|im_start|>system
  You are a helpful assistant.<|im_end|>
  <|im_start|>user
  Let $f(x) = x - 3$ and $q(x) = bx +1$.  If $f(q(1)) = -3$, what is $b$?
  Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
  <|im_start|>assistant
  
prompt.role: user
extra_info.answer: -1
extra_info.question: Let $f(x) = x - 3$ and $q(x) = bx +1$.  If $f(q(1)) = -3$, what is $b$?
extra_info.split: test