Basic problem

May 2010
3
0
Hey there!
I'm having alot of trouble with the following:

2 types of sacks
Large sacks weigh 30kg
Small sacks weigh 24kg
There are 3 times as much small sacks than there are large ones
The total weight of sacks is 714kg
How many large/small sacks are there?


All ive been able to do is
30x+24y=714
not sure how to continue
Please help
 
Dec 2009
3,120
1,342
Hey there!
I'm having alot of trouble with the following:

2 types of sacks
Large sacks weigh 30kg
Small sacks weigh 24kg
There are 3 times as much small sacks than there are large ones
The total weight of sacks is 714kg
How many large/small sacks are there?


All ive been able to do is
30x+24y=714
not sure how to continue
Please help
You forgot to formulate the blue line.

That then gives a pair of simultaneous equations for the two variables.
Or you can directly substitute.
 
Dec 2009
3,120
1,342
Aye, just really not sure how to do that :(
Ok,

you have labelled the large sacks "x"
and the small sacks "y"

hence y=3x is how we write "there are 3 times as many small sacks as large ones".

Whatever x is, y is 3 times that.

Now you have a choice....

(i) replace y with 3x in 30x+24y=714 to get 30x+24(3x)=714

and solve for x

(ii) solve the system of equations

3x=y
30x+24y=714

30x-10y=0
30x+24y=714

subtract the first line from the 2nd to get 34y=714

solve for y
 
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