Answer:
-18
Step-by-step explanation:
-15+6=-9
the absolute value of -9 is 9
and 9*-2=-18
Assuming the sequence goes on like this 11,-33,99,-297,891,...,
its general formula is

So, the 9th term is
Find the percentage of ratio to weight.
180/72 = 2.5
So 2.5 Earth Pounds = 1 Mars Pound
16*2.5 = 40 Pounds the rock weighs on earth.
The number = y
2y + 1/3 = 2/3 - 3y
(add 3y to both sides)
5y + 1/3 = 2/3
(subtract 1/3 from both sides to isolate y)
5y = 1/3
(divide by 5)
y = 1/15
Cross multiply
5/8 and 8/10
5x8=40
8x8=64
40 does not equal 64 so not proportional