Question

Find the value of X.

2x 14
---- = ----
5 30

Answer 1

Have you considered simplifying the right hand side?
Have you considered multiplying by 5?
Have you considered dividing by 2?

Answer 2

You can cross multiply

Answer 3

$$
\Large {
\frac{2x}{5} = \frac{14}{30}
\\ \iff\\
(2x)\cdot 30 = 14\cdot 5
}
$$

Answer 4

now solve for x , first simplify the left side

Answer 5

Do NOT "cross multiply". Why in the name of reason would you multiply by 30 just to divide by it again? It makes no sense.

Answer 6

I know how to cross multiply but Ive never done it like this for example I know how to do it his way

Answer 7

@perl @tkhunny

Answer 8

we can cross multiply that way, the two ways are equivalent

Answer 9

the order does not count

Answer 10

How is this.
$$
\Large {
\frac{2x}{5} = \frac{14}{30}
\\ \iff\\
5\cdot 14 = (2x)\cdot 30
}

$$

Answer 11

like that?

Answer 12

good so far

Answer 13

or would it look like this

Answer 14

$$
\Large {
\frac{2x}{5} = \frac{14}{30}
\\ \iff\\
5\cdot 14 = (2x)\cdot 30
\\ \iff \\
70 = 2x \cdot 30
\\ \iff \\
70 = 2\cdot 30\cdot x
}


$$

Answer 15

Oooh ok so then

Answer 16

perfect :)

Answer 17

now solve for x, divide both sides by ...

Answer 18

$$

\Large {
\frac{2x}{5} = \frac{14}{30}
\\ \iff\\
5\cdot 14 = (2x)\cdot 30
\\ \iff \\
70 = 2x \cdot 30
\\ \iff \\
70 = 2\cdot 30\cdot x
\\ \iff \\
70 = 60\cdot x


}


$$

Answer 19

Divide both sides by 60?

Answer 20

yes

Answer 21

@perl

Answer 22

did you divide both sides by 60 ?

Answer 23

$$
\Large {
\frac{2x}{5} = \frac{14}{30}
\\ \iff\\
5\cdot 14 = (2x)\cdot 30
\\ \iff \\
70 = 2x \cdot 30
\\ \iff \\
70 = 2\cdot 30\cdot x
\\ \iff \\
70 = 60\cdot x \\
\\ \iff \\
\frac{70}{60} = x

}

$$

Answer 24

@perl so does x = 1 or does x= 1.16 or is there more steps?

Answer 25

1.167 sounds correct.
you can also reduce the fraction to lowest terms

Answer 26

Ok thank you so much perl.

Answer 27

your welcome

Answer 28

Do NOT cross multiply. It doesn't mean anything.

\(\dfrac{2x}{5} = \dfrac{14}{30}\)

Simplify the right/

\(\dfrac{2x}{5} = \dfrac{7}{15}\)

Multiply by 5

\(2x = \dfrac{7}{15}\cdot 5\)

Simplify the right

\(2x = \dfrac{7}{15}\cdot 5 = 7\cdot\dfrac{5}{15} = \dfrac{7}{3}\)

Divide by 2

\(x = \dfrac{\dfrac{7}{3}}{2}\)

Simplify the right

\(x = \dfrac{\dfrac{7}{3}}{2} = \dfrac{7}{3}\cdot\dfrac{1}{2} = \dfrac{7}{6}\)

Simple, valid operations. "Cross Multiply" is neither.

Answer 29

@perl I have another equation like the one you helped me solve yesterday except this one is backwards. I think I understand it but can you check over my work to be sure?