8th Grade · Expressions & Equations
Define Variables
8.EE.C.8c
Definition
Assigning a distinct letter to each unknown quantity, with units, before setting up the equations of a system from a word problem.
Examples
- a = number of adult tickets, c = number of child tickets.
- Then write one equation per condition: a+c=10 and 8a+5c=68.
Key rule
Name each unknown with its own letter and units before writing equations.
Memory hook
One letter for each unknown.