All the choices are correct.
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In our base-10 number system, moving a digit one place to the left multiplies its value by 10. Moving it one place to the right multiplies its value by 1/10.
You know already that 1,000 has 10 times the value of 100, and 1/10 the value of 10,000.
-2x + 6y = -34
-x + 3y = -17
x = 3y +17
Sub this into 1st eqn
5(3y + 17) + 2y = 21
15y + 85 + 2y =21
17y = -64
y = -3.7647 (to 5 sig. fig.)
y = -3.8 (to nearest tenth)
Sub y = -3.7647 into 2nd eqn
x = 3(-3.7647) +17
x = 5.7 (to nearest tenth)
The greatest common fact or 32 and 96 is 2