To find out how many pens Kate has, we can set up the equation based on the information given. Mark has 10 pens, and Kate has 5 times as many pens as Mark.
Let \( y \) be the number of pens Kate has. The equation can be written as:
\[ y = 5 \times (10) \]
This simplifies to:
\[ y = 50 \]
Therefore, the equation that answers how many pens Kate has is:
\[ y = 5 \times 10 \] or simply \( y = 50 \).