\(Đặt:m_{CuSO_4\left(thêm\right)}=a\left(g\right)\\ V_{ddCuSO_4\left(sau\right)}=\dfrac{a+160}{1,25}\\ C_{MddCuSO_4\left(sau\right)}=1\left(M\right)\\ \Leftrightarrow\dfrac{\dfrac{a+160.5\%}{160}}{\dfrac{a+160}{1,25.1000}}=1\\ \Leftrightarrow a=14,312\left(g\right)\\ \Rightarrow m_{CuSO_4\left(thêm\right)}=14,312\left(g\right)\)