A pencil costs $p$ dollars and an eraser costs $e$ dollars. Mark buys $3$ more pencils than erasers, and he buys $7$ pencils. Write an expression that represents the amount of money that Mark spent, in dollars.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
A pencil costs $p$ dollars and an eraser costs $e$ dollars. Mark buys $3$ more pencils than erasers, and he buys $7$ pencils. Write an expression that represents the amount of money that Mark spent, in dollars.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
7p+4e
A pencil costs $p$ dollars and an eraser costs $e$ dollars. Mark buys $3$ more pencils than erasers, and he buys $7$ pencils. Write an expression that represents the amount of money that Mark spent, in dollars.
train