Question

using the sub. method.. 0.1x+0.9y=-6.8 and
0.6x-0.7y=8

Answer 1

finding the solution set..

Answer 2

first ditch those decimals, multiply everything by ten:
0.1x+0.9y=-6.8 and
0.6x-0.7y=8
Become:
x + 9y = -68
6x - 7y =80

Answer 3

ok

Answer 4

Substitution: x = -68 - 9y
6(-68 - 9y) - 7y = 80
Check it, then proceed

Answer 5

Multiply through
6(-68 - 9y) - 7y = 80
-408 - 54y - 7y = 80

Answer 6

Combine like terms:
-408 - 54y - 7y = 80
- 61y = 80 + 408
-61y = 488

Answer 7

y = 488/(-61)
y = -8

Answer 8

And it is -8 whether you multiplied by 10 in the very first step or not. Now find y.

Answer 9

i couldnot find the sub. #

Answer 10

got it thanks..