Detailed Instructions: In this task, you're given a sentence and your task is to generate a simplified sentence that focuses on lexical paraphrasing from the original sentence given in the input.
Q: in mathematics , a riemann sum is a method for approximating the total area underneath a curve on a graph , otherwise known as an integral.
A:
in math , a rieman sum is a way to estimate the area under a graph curve , known as an integr.