Use counters to subtract –2 − –7.

Question

You start with:

You subtract:

Which picture shows the difference?

Answer 1

To solve the expression \(-2 - (-7)\) using counters, follow these steps:

1. You start with: To represent \(-2\), you can use 2 red counters (representing negative quantities).

   \[ \text{Start with: } \text{R, R} \quad (\text{2 red counters}) \]

2. You subtract: Subtracting \(-7\) means you need to add 7 positive counters (since subtracting a negative is the same as adding a positive).

   \[ \text{You subtract: } \text{Y, Y, Y, Y, Y, Y, Y} \quad (\text{7 yellow counters}) \]

3. Combine the counters: Now you can combine the 2 red counters with the 7 yellow counters. Adding red and yellow counters together means you will obtain a total of 5 yellow counters after cancelling out the 2 red counters.

   \[ \text{Final Picture: } \text{Y, Y, Y, Y, Y} \]

Therefore, the difference \( -2 - (-7) = 5\). The picture showing the difference should show 5 yellow counters.