Question

Find the value of y when x equals 12.
x+3y=21

Answer 1

@Torvela

Answer 2

Plug in 12 for x and solve for y

Answer 3

Well I now the first step

Answer 4

(12) + 3y = 21

Answer 5

no nevermind

Answer 6

9
y=(21-12)/3

Answer 7

ok the way i think of these is I almost do it in reverse so take 12+3y=21 then subtract 12

Answer 8

from both sides

Answer 9

then divide each side by 3

Answer 10

9 is wrong

Answer 11

-9

Answer 12

no

Answer 13

?

Answer 14

osprey had correct formula wrong answer

Answer 15

ok, sorry. my arithmetic's obviously bad today. I apologise for the inconvenience, and I wish this screen would stop jumping about ! take care

Answer 16

ok start by doing 21-12

Answer 17

21-12=9

DOESN'T IT ????

Answer 18

9

Answer 19

yes but then you have to do 9/3

Answer 20

so 3

Answer 21

yup

Answer 22

that my awnser?

Answer 23

now fill in y to check answer

Answer 24

Torvela help me with another?

Answer 25

so yes 3 is correct answer do you understand how i did it or should i re-explain?

Answer 26

I think i understand I am not sure.... I was that guy who didn want you helping that one question with TG sorry about that tho

Answer 27

it's ok

Answer 28

I'm just sea sick from the jumping about of the postings is all !

Answer 29

btw jakob i always thought about doing it backwards/opposite of what the equation is after filling in x

Answer 30

so since you know that when you fill in x it becomes 12+3y=21

Answer 31

next start with the normal number/ numbers without variables so in this case 12 and since its positive subtract it from 21

Answer 32

now you have 3y=9 and all you have to do is divide 9 by 3 and you have the answer