Intermediate · 12 min
Working with expressions
Substitute values and simplify terms that describe the same quantity.
Substitute before calculating
Replace each variable with its value. Use brackets around negative values and follow the order of operations.
Worked example
If a = 4, then 3a + 2 = 3 × 4 + 2 = 14.
Collect like terms
Terms with the same variable part can be combined by adding their coefficients. A constant cannot be combined with an x term.
Worked example
3x + 2x − 4 = 5x − 4
Represent a cost
- Write an expression for x tickets at 9 each with a booking fee of 3.
- Evaluate it for 2 tickets and for 5 tickets.