Question

Solve for x

3x+3y=15
3x+2y=13

Medal and Fan!!

Answer 1

@phi

Answer 2

\[3x+3y=15\]
\[3(x+y)=15\]
\[x+y=5\]
??

Answer 3

????

Answer 4

i dont get it!!!!!

Answer 5

i'd say, try subtracting the 2nd equation from the 1st equation,
what u get ?

Answer 6

Okay so i at least know that you have to solve for x in the first equation then substitute x for the second equation. But i dont know how to do that!!

Answer 7

thats substitution method
what i suggested was elimination method

if you are more comfortable with substitution method,
you know you need to solve for x
have you tried, which step are u stuck ?

Answer 8

i just dont know how to solve for x in the first equation

Answer 9

start by factoring out 3 from left side
3x + 3y = 3 (...?..)

Answer 10

x=3

Answer 11

would i subtract 3 from both sides???

Answer 12

im confused!!!!!!!!!!!!!!!!!!!!!!!!!!!

Answer 13

When you see
3x+3y=15
3x+2y=13

you should notice that 3x - 3x is 0 (and the x's go away)
if you subtract the top equation minus the bottom equation, you will get
a new (improved!) equation with only a y. solve for y, then use that value in either of the original equations to find x.

Answer 14

(3x+3y=15) multiply by 2
(3x+2y=13) multiply by -3

result:

6x+6y=30
-9x-6y=-39

add the two equation using elimination method
-3x=-9
x=3

Answer 15

subract an equation means: multiply every term in the bottom equation by -1, then add term by term to the top equation

Answer 16

mine is a bit more complex than @phi... :D

Answer 17

y=2?

Answer 18

correct

Answer 19

Now use y=2 to find x

Answer 20

just substitute it to any of the 2 given eqation and you get x. :)

Answer 21

x=3?