Answer:
Equation to get b:
24 = 4 × (3+b)
Value of b:
b = 3 in
Explanation:
The image associated with this question is attached below
We know that the area of the rectangle is the product of its length and width
This means that:
Area of rectangle = length × width
We are given that:
length of postcard = 4 in
width of postcard = (3+b) in
area of postcard = 24 in²
Substitute with these givens in the equation and solve for b:
Area of postcard = length × width
24 = 4 × (3+b)
24 = 12 + 4b
24 - 12 = 4b
12 = 4b
b = 3 in
Hope this helps :)
