00:01
We're looking at this problem that involves fruit company boxes, large and small.
00:07
So there's two different deliveries, and this is going to help us create our two equations that we can use to figure out how much each box weighs.
00:17
So in the first delivery, we know that there are three large boxes, so three l, and eight small boxes.
00:26
So we're going to add eight small boxes.
00:29
Be careful with your s looking like a five that can make things much more confusing.
00:33
And we know that this is going to weigh 91 kilograms.
00:38
Now, the reason i'm writing it like this is because the total weight, which is that 91, is equal to the weight of each of the boxes, the large and the small, multiplied by however many boxes there are.
00:49
So if you can kind of picture this, this is sort of like saying, i've got three large boxes, i'll put them in red, and eight small boxes.
00:59
And when i put those together, like on a scale or something like that, it's equal to 91 kilograms.
01:08
That's the general idea behind this.
01:10
So for the second delivery, i'm not going to draw the picture.
01:14
We've got five large boxes and two small boxes.
01:19
And together, they weigh a little bit less, which is 78 kilograms.
01:24
Now, to solve this, we're going to use a strategy called elimination.
01:29
And elimination, the goal of it is to combine the two equations, usually by adding or subtracting them, to have one of the variables go to zero.
01:43
So we eliminate one of the variables.
01:45
In this case, what i'm noticing is that the variable s, the small boxes, 2s and 8s, 8 is a multiple of 2.
01:56
So if i can modify this second equation and make the two small boxes equal to eight small boxes from the first equation, then i can combine them and eliminate the small boxes to be left with just the large boxes.
02:12
So the way that i can do that is i have to think about what number can i multiply two by to get to eight, which is four.
02:20
Two times four is eight.
02:21
So i'm going to multiply this entire second line by four.
02:25
And then i'm just going to rewrite it over here on the right.
02:28
So i have four times five l.
02:33
So that gives me 20 large boxes plus four times 2s, which is the eight that i was looking for, 8s, equal to four times 78.
02:45
So it's literally just scaling the entire thing.
02:48
And that's equal to 312.
02:51
78 times four is 312...