Question

what is the area of rectangle abcd?

Explanation:

Step1: Find length of AB

Count vertical grid units: From $A(0,-1)$ to $B(0,4)$, the length is $4 - (-1) = 5$. Each grid is 2 units, so $AB = 5 \times 2 = 10$.

Step2: Find length of BC

Count horizontal grid units: From $B(0,4)$ to $C(4,4)$, the length is $4 - 0 = 4$. Each grid is 2 units, so $BC = 4 \times 2 = 8$.

Step3: Calculate rectangle area

Area = length $\times$ width, so $Area = AB \times BC$.
<Expression>
$Area = 10 \times 8 = 80$
</Expression>

Answer:

80