Density=mass/volume
given mass=120g and volume=200cm3
density=

or abot 0.6
the density is
Answer:
A
Step-by-step explanation:
Answer with positive exponent =
or 
Answer with negative exponent = 
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Explanation:
The rule we use is

If we multiply two exponential expressions with the same base, then we add the exponents.
The base for each is 5. The exponents 4 and -7 add to -3.
This means

To convert to a positive exponent, we apply the reciprocal to the base. We go from 5, aka 5/1, to 1/5.
So, 
X = 25.5 mm.
Using the similarity statement given, that ΔABC ~ ΔDEF, we set up a proportion:
8.5/x = 4/12
Cross multiply:
4*x = 8.5*12
4x = 102
Divide both sides by 4:
4x/4 = 102/4
x = 25.5