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the_hill1962
Advanced Member
USA
1438 Posts |
 Posted - 09/10/2007 : 14:03:58
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Let c=amount of cement
and g=amount of gravel
So, "four times as much gravel as cement" means g=4c (how do you figure that the equation is g=4c ??? --- because there was more gravel, you multiply the amount of cement by 4).
The other equation is easy to get, "total volume is 22.5" means c+g=22.5
You can substitute "4c" for "g" into the cg=22.5 since g=4c.
See how it works------c+g=22.5 becomes c+4c=22.5
Now that simplifies to 5c=22.5 which means c=4.5
and since g=4c, g=4 4.5=18. Of course you need to indicate the unit |
Edited by - the_hill1962 on 09/10/2007 14:11:11 |
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. How much of each was in the mix? 
