Ahorse drinks about 120 gallons of water every four days at this rate about how many gallons of water does a horse drink in 28 days

First you want to divide 28 by 4, because it's counting in 4 day intervals and this will narrow it down to the average days.  This gives you 7, which you now multiply by 120, which gives you a total of 840 gallons within a period of 28 days.

X= 49; x = 4step 1: foilstep 2: equal both to 0step 3: find x individually