The signed number that represents Kira's loss of 70 dollars is -$70, with the negative sign indicating a decrease in her money.
The signed number to represent Kira losing 70 dollars is - $70.
In mathematics, positive numbers typically represent gaining or adding something, while negative numbers represent losing or subtracting something.
Therefore, a loss of money is shown as a negative number.
For example, if someone gained 70 dollars, it would be represented as +$70.
Conversely, the loss is represented as -$70, indicating that the amount of money Kira has decreased by that amount.