Answer:
The answer is B!
Step-by-step explanation:
Add 1 to both sides, then divide 80 by 9!
Answer: 10
<u>Step-by-step explanation:</u>
varies directly means: 
Step 1: solve for k ⇒ 
Step 2: plug in the given value and k to solve for the missing value: 
42(5) = 21(x)

2(5) = x
10 = x
Answer:
The answer to your question is below
Step-by-step explanation:
pH definition
pH = - log [H⁺]
a) For pH = 2.4, solution A
2.4 = -log[H⁺]
[H⁺] = antilog⁻².⁴
[H⁺] = 0.00398
For pH = 9.4, solution B
[H⁺] = antilog⁻⁹.⁴
[H⁺] = 3.98 x 10⁻¹⁰
b) Divide hydrogen-ion concentration of solution A by hydrogen-ion concentration of solution B.
0.00398 / 3.98 x 10⁻¹⁰
10000000 times
c) By 7, because 7 is the number of zeros