Answer:
y is also doubled.
Step-by-step explanation:
Direct proportionality between
and
means that

or
,
which indicates a linear relationship between
and
because they are related by a constant.
Therefore, if x is doubled, then the new value of
is 



The new value of
is 2 times the previous; therefore,
is doubled as
is doubled.
Answer:
- points on the boundary line: (0, 10), (20, 0)
- solution points not on the boundary line: (100, 100)
Step-by-step explanation:
We cannot tell from the posted picture whether the boundary line is solid or dashed, so the answer above is split into two parts. If the boundary line is solid (x+2y≥20), all three listed points are in the solution set. If the boundary line is dashed (x+2y>20), only (100, 100) is in the solution set.
11. Assuming distance is proportional to time,
.. (3 h)/(7 h) = d/(665 km)
.. d = (665 km)*(3/7) = 285 km . . . . . . selection B
12. (30 L)/(1.5 L/min) = 20 min . . . . . . selection C
A negative cannot be a root, 8= 2.4
The final step in solving the inequality=
-6<-2x
-2x>-6
x<3