Exercise algebra.manipulation.rational.simplify

Description
simplify a rational expression (with a variable in a divisor)

Derivation

4/(3*a)-2/(5*b)

⇒ algebra.equations.rational.rational-scale

20*b/(15*a*b)-6*a/(15*a*b)

⇒ algebra.equations.rational.rational-plus

(20*b-6*a)/(15*a*b)