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00:34order of operations and substitution in math before watching this video.
00:40What is the value of 3f divided by 4 minus g divided by 2 when f equals 12 and g equals 8?
00:49To solve this problem, we need to know about substitution and about the order of operations.
00:55When a letter is written next to another number, that means they are being multiplied.
01:01We'll rewrite this expression with an asterisk to show the multiplication.
01:06This shows the number 3 being multiplied by the letter f. We bring down the other numbers and operators.
01:13Next, we'll replace the horizontal bars with division signs. We rewrite this one as g divided by 2.
01:20This numerator is more complicated. It contains a number, a letter, and an operator. In this case,
01:26the number is 3, the letter is f, and the operator is the multiplication sign.
01:31We need to put the entire numerator inside a set of parentheses to show that the product of this
01:36multiplication is being divided by 4. Now, we're ready to do the substitution.
01:43We substitute the letter f with the number 12. And we substitute the letter g with the number 8.
01:51Next, we need to know which order to do the operations in.
01:55Here's a reminder of the order of operations. For elementary school, they're free boxes.
02:00The order of operations tells us which order to do things in.
02:04We start with the top box, then do the middle box, then do the bottom box.
02:09The order is parentheses, then multiply and divide, then add and subtract.
02:14One way to remember what words go in each box is to use a memory aid like this sentence.
02:20Please make drinks and sandwiches. The first letter of each word in the memory aid
02:24is the same as the first letter in the order of operations. We also write in a reminder that
02:30if both are present, then do the left ones before the right ones.
02:35Since there are parentheses, we start with the parentheses.
02:383 times 12 equals 36. We bring down the other numbers and operators.
02:44Now we go down to the red box, which stands for multiplication division.
02:48There are two division operations. 36 divided by 4 equals 9. A divided by 2 equals 4.
02:554. There's only one operation left, which it is subtraction. 9 minus 4 equals 5.
03:06Choice C is correct. Thanks for your attention.
03:25Alice did for your attention on that.
03:28Here we go.
03:31Awesome, thanks, sir.
03:48Okay, thank you.
03:49You
