ShmoopTube

Where Monty Python meets your 10th grade teacher.

Search Thousands of Shmoop Videos

CAHSEE Math 4.4 Number Sense 195 Views


Share It!


Description:

Number Sense: Drill Set 4, Problem 4. Solve the expression.

Language:
English Language

Transcript

00:03

Here's your shmoop du jour.

00:06

2/5 divided by... 1/15 minus 3/10 equals...what?

00:12

And here are the potential answers...

00:16

Well, this question isn't big on words -- it's just asking whether we can subtract and divide fractions.

00:21

Piece of cake. Because we don't want to make PEMDAS mad,

00:24

we start with the junk inside the parentheses.

00:28

First we have to get a common denominator for 15 and 10.

00:34

Both fit into 30 pretty easily... in that case, let's multiply top and bottom of 1

00:38

over 15 by 2 to become 2 over 30...

00:43

...then we multiply top and bottom of 3 over 10 by 3 to get 9 over 30.

00:49

2 minus 9 is -7... so we can rewrite the problem now as 2 fifths divided by -7 over 30.

00:56

And remember that dividing by a fraction is the same thing as multiplying by its inverse.

01:01

So rewrite the problem as:

01:03

Two fifths TIMES -30 over 7

01:07

And we have -60 over 35

01:10

We can reduce that bad boy to -12 over 7 and voila -- it's answer A.

01:15

Thank goodness. Now we won't have to deal with the wrath of PEMDAS.

Up Next

CAHSEE Math 5.3 Algebra and Functions
2032 Views

CAHSEE Math: Algebra and Functions Drill 5, Problem 3. Solve the equation.

Related Videos

Operations with Rational Expressions
8687 Views

It's impressive that these expressions are able to stay so rational even when they're having operations performed on them.

Numbers and Operations: Elementary Number Theory
605 Views

Jack and Jill went up the hill to fetch a pail of water. But what happened when they got up there? They’ve been gone an awfully long time…

SAT Math 7.3 Algebra and Functions
318 Views

SAT Math 7.3 Algebra and Functions

SAT Math 6.4 Algebra and Functions
486 Views

SAT Math 6.4 Algebra and Functions