I think i get this answers right but my teacher mark it wrong i dont know why can you help me sovle this ?

Question

If 7 + 3x = 22, then 2x = ?

F. 5

G.10

H.12

J.14

k.58/3

can you work the problem out for me too thank you very much !!!!!

^_^

Answer 1

(a) 3x=15 -> x=5 -> 2x=10 (G)

(b) 2/3 *F = 0.15  -> F=0.225

Answer 2

first question first!!!

7+3x=22

7+3x-7=22-7   (isolate the variable, then "whatever you do on one side        must be done to the other side as well".)

3x=15  /3   (again, isolate the variable, so divide BOTH sides by 3.

x=5.

if x=5, then 2x = 5x2, which is 10.

The answer is G.

for the second question, i cant help you as i no longer take science :)

hope i helped on the first one tho!

Answer 3

First question:

7 + 3x = 22

7 - 7 + 3x = 22 - 7   Subtract 7 from both sides

3x = 15

3x/5 = 15/5  Divide both sides by 3

x = 5

So if x=5, 2x = 10.  The answer is G.

Second question:

L = (2/3)F + 0.03

So when L = 0.18, find F

0.18 = (2/3)F + 0.03

0.15 = (2/3)F   Subtract 0.03 from both sides

0.225 = F     Divide both sides by 2/3

Answer 4

  The answer is10.

     7+3x=22 , 2x=?

      Your first step is to transpose. This means to move an expression to the other side.

   7+3x-7=22-7=15

   Therefore, 3x=15

   15/3=5

    x=5,  2x=10

   If you follow these rules , you should get the right answer.

   If your teacher still marks it wrong, ask her why?  Sometimes  in math theorem, the instructor will look at each step , and judge accordingly. Me, I don't see why it matters

as long as you get the right answer. However, if you're wanting to teach math, it might matter.

                       Keep studying

Answer 5

Solve the first equation for x, then substitute that value for x in:

2x = ?

7 + 3x = 22

subtract 7 from both sides of the equation (you are isolating the terms involving the variable)

3x = 15

Well, that shouldn't be too hard:  x = 5

Now, if x = 5, then 2x = ?

2x = 10