\(\begin{array}{l}
a)\\
CuO+H_2SO_4\to CuSO_4+H_2O\\
n_{CuO}=\frac{12}{80}=0,15(mol)\\
n_{CuSO_4}=n_{CuO}=0,15(mol)\\
m_{CuSO_4}=0,15.160=24(g)\\
b)\\
n_{H_2SO_4}=n_{CuO}=0,15(mol)\\
m_{dd\,H_2SO_4}=\frac{0,15.98}{25\%}=58,8(g)\\
c)\\
m_{dd\,spu}=12+58,8=70,8(g)\\
C\%_{CuSO_4}=\frac{24}{70,8}.100\%\approx 34\%
\end{array}\)