Jerome bought 5 x 2 = <<5*2=10>>10 toy cars this month.

So he bought a total of 5 + 10 = <<5+10=15>>15 toy cars.

Therefore, Jerome had 40 - 15 = <<40-15=25>>25 toy cars originally.

# Answer

25
<|im_start|>system
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<|im_start|>user
Jerome bought 5 new toy cars last month. This month he bought twice as many so that he has 40 toy cars now. How many toy cars did Jerome have originally?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
25
Jerome bought 5 new toy cars last month. This month he bought twice as many so that he has 40 toy cars now. How many toy cars did Jerome have originally?
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