6.5 is equal to 65/10 the reciprocal of that is 10/65=2/13
C. liquid to solid.
When things get cooler, they go from gas to liquid to solid. If you know water is a solid, and you know it's cooling and changing states, then you can correctly infer that it is changing from a liquid to a solid.
So to start you need to add 7 and 4 to get 11
Then you divide 1650mL by 11 which gets you 150mL
You then times that by 7 to get the ratio of blue paint which is 1050mL and times 150mL by 4 to get the ratio of red paint which is 600mL