To determine if Santiago bought 10 board books and 5 soft cover books for exactly $20, we can calculate the total cost.
The cost of 10 board books: \(10 \times 1.50 = 15.00\)
The cost of 5 soft cover books: \(5 \times 0.50 = 2.50\)
Now sum the costs: \(15.00 + 2.50 = 17.50\)
The total cost of the books is $17.50, not $20.
Therefore, the statement is false.