simultaneous equation 

equations involving two or more unknowns that are to have the same values in each equation.

If an equation has two unknowns, such as 2y + x = 20, it cannot have unique solutions. Two unknowns require two equations which are solved at the same time (simultaneously) − but even then two equations involving two unknowns do not always give unique solutions.
This gives us a 'simultaneous equation'

simultaneous equation by rieazen September 9, 2014

Explain Simultaneous Equations

The thing you ask your stupid friend to define as a test of intelligence.

"Explain Simultaneous Equations."
"I can't, I'm too stupid."

Explain Simultaneous Equations by HappyCrocodile24 March 27, 2023