<PRE><B>Question 176332</B>
Let x=length of 30ml storm
then 45-x=length of the 15ml storm
Amount of rainfall for the 30ml storm=30x
Amount of rainfoall for the 15ml storm=15(45-x)

Now we know that the total amount of rainfall equals the sum of the above two amounts, so:
30x+15(45-x)=975  get rid of parens
30x+675-15x=975 subtract 675 from each side
30x-15x+675-675=975-675  collect like terms
15x=300 divide each side by 15
x=20 hr----------------------------------length of 30ml storm
45-x=45-20=25 hr------------------------------length of 15ml storm

CK
20*30+25*15=975
600+375=975
975=975

Does this help??------ptaylor</PRE>