They sold 40 erasers because 20 x 2 = <<20*2=40>>40

Therefore 20(Pencil Price) + (1/2)(40 x Pencil Price) = 80

Therefore 40(Pencil Price) = 80

Therefore (Pencil Price) equals 2 because 80 / 40 = <<80/40=2>>2

An eraser costs $1 because 2 / 2 = <<2/2=1>>1

# Answer

1
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
A store sells pencils and erasers. It has a rule that for every pencil you buy, you must buy 2 erasers which cost 1/2 the price of the pencils. If they sold 20 pencils and earned $80, how much do erasers cost?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
1
A store sells pencils and erasers. It has a rule that for every pencil you buy, you must buy 2 erasers which cost 1/2 the price of the pencils. If they sold 20 pencils and earned $80, how much do erasers cost?
train