Answer:
0.75
Step-by-step explanation:
Given a geometric sequence: 
The common ratio is derived by dividing any next term by the preceeding term.
That is:

In the geometric sequence: 4,3,9/4
Common ratio, 
The common ratio of the given geometric sequence is 0.75.
Step-by-step explanation:
10 %, 7/10 and 0.2 are the three numbers that add up to 1
0.1 + 0.7 + 0.2 = 1
.28 if 1 was 100,and .28 was 2.8, then we divide 100 by 100 same for 2.8
Draw a right triangle ABC so that m∠C = 90°
The lengths are:
Side a is opposite ∠A,
Side b is opposite ∠B,
Side c (the hypotenuse) is opposite ∠C
Because cos A = x, therefore
x = b/c => b = cx (1)
Because sin A = y, therefore
y = a/c => a = cy (2)
By definition,
tan A = a/b
= (cy)/(cx)
= y/x
Answer: b. y/x
2(a+bc)=2a+2bc
3.(ab-cb-ba+bc)= 3ab-3cb-3ba+3bc
Since the brackets and multiplication have a higher order than the rest.
Cb=Bc
Ab=ba
Ac=Ca
Because multiplication is commutative.
2a+2bc + cb +ab + ac -(3ab-3cb-3ba+3bc)
2a + 2bc + cb + ab + ac(+ -3ab - - 3cb - -3ba +-3bc)
2a + 2bc + cb + ab + ac -3ab + 3cb + 3ba -3bc
2a + (2bc-3bc +cb + 3cb ) + (ab -3ab + 3ba) + ac
=2a + 3cb + ba+ ac OR 2a +3bc + ab + ac
The Or is just a different way to write it.
Hope this helps