Question

rút gon 

Answer 1

\(=\dfrac{5x\left(3x+1\right)}{3x+1}=5x\)

Answer 2

\(\dfrac{5x\left(3x+1\right)}{3x+1}=5\)

Answer 3

\(\dfrac{15x^2+5x}{3x+1}\)

\(=\dfrac{5x\left(3x+1\right)}{3x+1}=5x\)