Radio Barn : 200 + .15 x x = the weekly sales
Woofer: 300 + .10x
set them equal to find when they are them same
200 + .15x = 300 + .10x
subtract .10x from both sides
200 +.15x -.10x = 300 + .10x-.10x
200 +.05x = 300
subtract 200 from each side
200+.05x -200 = 300-200
.05x = 100
divide each side by .05
.05x/.05 = 100/.05
x =2000
The 2 jobs pay the same when the weekly sales are 2000 dollars
2. {x - 5 = -y}
{2y - 10 = -2x}
x-5 = -y
add 5 to each side
x = -y+5
multiply each side by -2
-2x = 2y -10
the 2 equations are the same, it has an infinite number of solutions
The system is dependent since the 2 equations are the same line
3. {2x = y - 7}
{4x - 2y - 14 = 0}
2x = y-7
subtract y-7 from each side
2x - (y-7) = 0
2x -y+7 =0
multiply by 2
4x -2y +14 =0
subtract the two equations
4x -2y +14 =0
4x - 2y - 14 = 0
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28 = 0
since this cannot happen the lines will never cross ( parallel lines)
the system is inconsistent
