A fork of Rural Dictionary
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'
The thing you ask your stupid friend to define as a test of intelligence.
"Explain Simultaneous Equations." "I can't, I'm too stupid."