Let the side of one square be x.   Area = x*x = x²
Then the side of other square would be 2x ,  Area = 2x*2x = 4x²
Combined area = x² + 4x² = 5x²
This combined area = 45 cm²
Therefore 5x² = 45  Divide both sides by 5
                 x² = 45/5
                 x² = 9       Take square root of both sides
                 x  = √9
                 x = 3
Length of larger square is 2x = 2*3 = 6 cm
Length of larger square = 6cm
