To evaluate an expression when x = 7 and y = 6, we substitute those values into the expression and calculate the result.
Let's assume we have an expression: 2x + 3y - 4.
Substituting x = 7 and y = 6:
2(7) + 3(6) - 4
= 14 + 18 - 4
= 28.
Therefore, when x = 7 and y = 6, the expression 2x + 3y - 4 evaluates to 28.