we make a relation

now we make a relation between the number of gallons on 1 day

where x is the number of gallons on 1 day
Join it

and use cross multiplication to solve, multipli the numbers on the diagonal where isnt the missing number. and divide by the number on diagonal of the missing number, to find the Value of the missing number
to simplify the operations we change the mixed number to decimal

then...

and do the operations to find the unknow

the reounded number of gallons for one day are
