D. would be the right answer mate
City A and City B are about 76.5 miles apart because 51*1.5 = 76.5
You might have made an error the first time you solved for x. I got x = -0.5.
When you have your log base 4, the way you cancel that out is by making 4 the base on both sides, so you get 4^(log4) to reduce to 1, and you're left with:
2x + 3 = 4^(1/2) ... Simplify
2x + 3 = 2
2x = -1
x = -1/2
If you plug that back in, everything checks out. Maybe double check your use of logarithm/exponent properties?
Those expressions are already in scientific notation.
Answer:
Number of high quality version downloads = 880
Step-by-step explanation:
Let,
x be the number of standard version songs downloaded
y be the number of high quality version songs downloaded
According to given statement,
x+y=1600 Eqn 1
2.8x+4.1y=5624 Eqn 2
Multiplying Eqn 1 by 2.8 to eliminate x
2.8(x+y=1600)
2.8x+2.8y=4480 Eqn 3
Subtracting Eqn 3 from Eqn 2
(2.8x+4.1y)-(2.8x+2.8y)=5624-4480
2.8x+4.1y-2.8x-2.8y=1144
1.3y=1144
Dividing both sides by 1.3

Hence,
Number of high quality version downloads = 880