We can solve this system of equations by multiplying the first equation by 3 and the second equation by 2, and then subtracting the second equation from the first to eliminate y:
9x + 6y = 144
4x + 6y = 24
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5x = 120
Dividing both sides by 5, we get:
x = 24
Substituting this value of x into either of the original equations, we can solve for y:
3x + 2y = 48
3(24) + 2y = 48
72 + 2y = 48
2y = -24
y = -12
Therefore, x - 2y = 24 - 2(-12) = 24 + 24 = 48.
Rounding to the nearest tenth, we get:
x - 2y = 48.0.