Question 137640
let x="time combined" __ (x/18)+(x/25)=1


they each fill some fraction of the pool based on the combined time and their individual time
__ the fractions sum to 1 (the entire pool being filled)


multiplying by 450 (the LCD) __ 25x+18x=450 __ 43x=450 __ x=450/43 __ about 10.5