A unitless ratio measuring the amount of water to cement, expressed as a decimal fraction.

Every gallon of water weighs 8-1/3 pounds

Every sack of cement weighs 94 pounds

Multiply the number of gallons of water by 8.333

Multiply the number of sacks of cement by 94

Divide the former by the latter. The result is the water to cement ratio.

((Num. Gal. Water)*8.333)/((Num. Sacks of Cement)*94)