Question

Use counters to subtract –2 − –7.

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.