### Instruction: On an algebra test, there were $5x$ problems. Lucky Lacy missed $x$ of them. What percent of the problems did she get correct?### Response: I need to find the ratio of the problems Lacy got correct to the total number of problems, and then multiply by 100 to get the percentage.
She got correct $5x - x = 4x$ problems, since she missed $x$ of them.
The total number of problems was $5x$.
So the ratio is $\frac{4x}{5x} = \frac{4}{5}$.
Multiplying by 100, I get $\frac{4}{5} \times 100 = 80$.