Answer
Between 4170 and 6712 gallons
Work Step by Step
Let g be the number of gallons. The charge for up to 7500 gallons of water is $10.40+0.0059g$.
Write and solve an expression showing the water charge between \$35 and \$50 inclusive.
$35\leq10.40+0.0059g\leq50\longrightarrow$ subtract 10.40 from each part
$35-10.40\leq10.40+0.0059g-10.40\leq50-10.40\longrightarrow$ subtract
$24.60\leq0.0059g\leq39.60\longrightarrow$ divide each part by 0.0059
$24.60\div0.0059\leq0.0059g\div0.0059\leq39.60\div0.0059\longrightarrow$ divide
$4169.5\leq g\leq 6711.9$
