Answer:
[tex]\boxed{\textbf{24 cards}}[/tex]
Step-by-step explanation:
[tex]\begin{array}{rcl}x & = & \text{Kiara's cards}\\3x & = & \text{Three times Kiara's cards (Rob's cards)}\\x + 3x& = & \text{Total cards}\\4x & = & 32\\x & = & \mathbf{8}\\3x & = & 3 \times 8 = \mathbf{24}\\\end{array}[/tex]
[tex]\text{Rob has $\boxed{\textbf{24 cards}}$}[/tex]
