Question

Solve using the substitution method.
8x – 5y = 3

7x + y = 51

Answer 1

so re shape the second equation to be y = ...
\[y=51-7x\]
now substitute this into your first equation for y

Answer 2

\[8x-5(51-7x)=3\]
and solve for x

Answer 3

i dont know what to do next

Answer 4

expand the bracket,
ie -5 times 51 , and -5 times -7x

Answer 5

8x-225-35x=3

Answer 6

careful now
-5 times -7x is +35x

Answer 7

the x needs to cancel next right?

Answer 8

yeah

Answer 9

thanks

Answer 10

\[8x – 5y = 3\]\[8x-5(51-7x)=3\]\[8x-225+35x=3\]
...

Answer 11

43x=222

Answer 12

check that again
we are adding 225 to both sides

Answer 13

8x-225+35x=3
+225 +225
cancel
8x+35x=228

Answer 14

that is good

Answer 15

im not done tho right?

Answer 16

i am not getting a nice answer for this question

Answer 17

i keep getting
x=228/43

Answer 18

me too..that is why i asked for help bc i questioned myself

Answer 19

but i think ive made an error somewhere

Answer 20

x=6,y=9 is a working solution but im not sure how to get there, or what we did wrong

Answer 21

i will turn in what we did and get sum feedback

Answer 22

5 x 51 = 255

Answer 23

\[8x-5y=3\qquad (i)\]\[7x+y=51\qquad(ii)\]

\[(ii)\rightarrow\qquad y=51-7x\qquad(iii)\]\[(iii)\rightarrow(i)\qquad 8x-5(51-7x)=3\]\[\qquad 8x-255+35x=3\]\[\qquad\qquad 43x=258\]\[x=\frac{258}{43}\]\[x=6\qquad (iv)\]

\[(iv)\rightarrow(ii)\qquad 7(6)+y=51\]\[42+y=51\]\[y=9\]