Which equation has exactly one solution?

4x - 7 = -3(3 + 4x)
4x - 7 = 0.5 (3 + 8x)
4x - 7 = 0.5 (-14 + 8x)
-12x - 7 = -3(3 + 4x)

Several paint mixtures are made by mixing blue paint and white paint. paint colors blue paint white paint mixture a 5 cups 12 cups mixture b 6 cups 6 cups mixture c 4 cups 12 cups mixture d 5 cups 6 cups which mixture has the highest ratio of blue paint to white paint