Bài 1:
a: \(\dfrac{3x}{5x+5y}-\dfrac{x}{10x-10y}\)
\(=\dfrac{3x}{5\left(x+y\right)}-\dfrac{x}{10\left(x-y\right)}\)
\(=\dfrac{6x\left(x-y\right)-x\left(x+y\right)}{10\left(x-y\right)\left(x+y\right)}\)
\(=\dfrac{6x^2-6xy-x^2-xy}{10\left(x-y\right)\left(x+y\right)}\)
\(=\dfrac{5x^2-7xy}{10\left(x-y\right)\left(x+y\right)}\)