A photograph has a length that is 3 inches longer than its width, x. So its area is given by the expression x(x + 3) square inches. If the area of the photograph is 70 square inches, what is the width of the photograph?
The area of the photograph is given by x(x + 3) square inches.
Setting this expression equal to 70, we have: x(x + 3) = 70.
Expanding the left side of the equation, we get: x^2 + 3x = 70.
Rearranging this quadratic equation in standard form, we have: x^2 + 3x - 70 = 0.
This can be factored as (x + 10)(x - 7) = 0.
Setting each factor equal to zero, we have: x + 10 = 0 or x - 7 = 0.
Solving for x, we find x = -10 or x = 7.
Since the width of the photograph cannot be negative, the width of the photograph is x = 7 inches. Answer: \boxed{7}.