# Basic problem

#### matchbox

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

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
You forgot to formulate the blue line.

That then gives a pair of simultaneous equations for the two variables.
Or you can directly substitute.

#### matchbox

You forgot to formulate the blue line.

That then gives a pair of simultaneous equations for the two variables.
Or you can directly substitute.
Aye, just really not sure how to do that 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

• matchbox

#### matchbox

Now i understand. Thanks again 