Question

In the equation 3x + 4y = 9, find x if 2y = 6.
A. -2
B. -1
C. 0
D. 1

Answer 1

if 2y=6 then 4y=2(6)=?

Answer 2

then insert that number in place of 4y
and solve for 3x
then x

Answer 3

is it 0?

Answer 4

let's go in little bitty steps

Answer 5

2y=6
so if I multiply 2 on both sides
I get
2(2y)=2(6)
so 4y=?

Answer 6

12?

Answer 7

perfect!:)
\[3x+4y=9 \\ 3x+12=9 \text{ solve this equation for } x \]

Answer 8

So I replaced 4y with 12

Answer 9

now all have to do is solve 3x+12=9 for x
Here is one step 3x=9-12

Answer 10

what do i do?

Answer 11

you are solving for x

Answer 12

you had 3x+12=9
I subtracted 12 on both sides for you
and gave you 3x=9-12

Answer 13

find the difference of 9 and 12

then divide both sides by 3 to get x by itself

Answer 14

9*3=27 12*3=36

Answer 15

9-12 is -3 isn't it?

Answer 16

yes

Answer 17

3x+12=9
Subtracted 12 on both sides
3x=9-12
so
then 3x=-3

Answer 18

now I actually gave you the last step to perform
which was to divide both sides by 3

Answer 19

9?

Answer 20

are you not wanting to divide?

Answer 21

\[3x=-3 \\ \text{ divide both sides by 3 } \\ \frac{3x}{3}=\frac{-3}{3} \\ x=\frac{-3}{3}\]

Answer 22

how many times does 3 go into -3?

Answer 23

1

Answer 24

well -1 times

Answer 25

-3/3 is -1

Answer 26

not 9 or -9

Answer 27

-3(3)=-9 but we had -3/3

Answer 28

ok..thanks so much!