Original measures of the tinplate square: x cm * x cm
Measure of thesides of the tinplate after cutting two 4 cm square pieces out of each side: [x - 8]*[x - 8] (this is the base of the container)
Volume of the container =: area of the base * height
area of the base = [x - 8]^2
height = 4 cm
Volume of the container 4*[x - 8]^2 = 120 cm^3
Divide both sides by 4: [x - 8]^2 = 30 cm^2
Extract square root from both sides: [x - 8] = √(30 cm^2)
[x - 8] ≈ 5.5 cm
x ≈ 5.5cm + 8 cm ≈ 13.5 cm
Answer: the side of the original tinplate square was approximately 13.3 cm
