Hello I'm looking for someone to help explain this to me...

-7/20x= -21/10

(4.9-18.6)x 13

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- Oct 12th 2007, 10:40 PM #1danielle77Guest

- Oct 13th 2007, 01:11 AM #2

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Add brackets to make the intended meaning clear. Is this:

(-7/20) x = -21/10

if so multiply both sides by -10/7 to get:

(-10/7)(-7/20) x = (-10/7)(-21/10)

which is:

(1/2)x = 3

or x=6

(4.9-18.6)x 13

RonL

- Oct 13th 2007, 09:08 PM #3jsebringGuest
## multiply by the reciprocals

your problem, -7/20x=-21/10

the solution multiply both sides by the reciprocal of -7/20 which is -20/7

that will isolate x, so your prblem should look like this x=-21/10 x -20/7

from there you you break the numbers into their prime factorization

21/10 = 3x7/2x5 and -20/7 = 2x2x5/1x7

now your numerator should look like this 3x7x2x2x5

and your denominator should look like this 2x5x1x7 your next step is to multiply 2/2 x 5/5 x 7/7 x 3x2/1 because any number divided by itself is one those first three numbers cancel out and your left with 3x2/1 which equals 6/1 or 6

hope this helps it should make more since once you write it out