given that 1 litre is 1.75 pints and 1 gallon=8 pints

Answer:
The required coordinates of Point C are [tex]\left(15,\:16\right)[/tex]
Explanation:
[tex]\mathrm{Midpoint\:of\:}\left(x_1,\:y_1\right),\:\left(x_2,\:y_2\right):\quad \left(\frac{x_2+x_1}{2},\:\:\frac{y_2+y_1}{2}\right)\\\\C-cordinates=\left(\frac{27+3}{2},\:\frac{30+2}{2}\right)\\\\=\left(15,\:16\right)[/tex]
Best Regards!