# Revision history [back]

### how to substitute several variables on both sides of the equation?

This is my worksheet: https://cocalc.com/share/f7766c5e-2f4d-4916-bb0d-74a7182e5fd5/2019-02-09-203517.sagews?viewer=share

I would like to substitute

V == 4*pi*p_ges/U


in line 36 in the equation

 SR.symbol('p_ges') == p_ges_rhs


but those variables are spread out over both sides of the equation, and i am clueless as to how to convince sage that this is a good idea. :-) How can I transform this equation in this way? Do i need to do this manually and re-write p_1 -p_4 accordingly?