the first answer choice, associative property of addition
hope this helps. gl!
5) 1.1802 x 10^6
6) 0.00016
7) 4.3 x 10^-3
8) 2,835,000
Step-by-step explanation:

Answer:
x=17/3, y=10/3. (17/3, 10/3).
Step-by-step explanation:
4x-5y=6
2x+5y=-28
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4x-5y=6
-2(2x+5y)=-2(-28)
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4x-5y=6
-4x-10y=56
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-15y=-50
15y=50
y=50/15
y=10/3
4x-5(10/3)=6
4x-50/3=6
4x=6+50/3
4x=18/3+50/3
4x=68/3
x=(68/3)/4
x=(68/3)(1/4)=68/12=17/3