In a mixture of concrete there are two lb of cement mix for each pound of gravel. If the mixture contains a total of 54lbs of these two ingrediants, how many pounds of gravel are there?

Question

perl · Answer

Solve the proportion : 
2 lb cement / 1 lb gravel = (54 - x) / x

anonymous · Answer

I don't know how to solve these well can you show me how

perl · Answer

solve  2/1 = (54 - x ) / x  
 you can cross multiply

anonymous · Answer

how do you cross multiply?

perl · Answer

2 * x = 1 * ( 54 - x )

perl · Answer

2x = 54 - x 
3x = 54
x = 18

perl · Answer

so in a 54 pound mixture of concrete there are 18 pounds of gravel and 36 pounds of cement

anonymous · Answer

thank u

perl · Answer

sorry i couldnt draw it out, the draw button is broken

anonymous · Answer

its ok thnks