Answer:
7cm
.
Step-by-step explanation:
Area = Length (L) * width (W)
L = 3 + w
Area = 70cm²
70 = (3 + w) * w
70 = 3w + w²
w² + 3w - 70 = 0
w² + 10w - 7w - 70 = 0
w(w + 10) - 7(w + 10) = 0
w + 10 = 0
w - 7 = 0
w = - 10 or w = 7
Widyh cannot be negative
Hence, width = 7
