U can use the second last one
X + 90 = 2x + 40
Answer:
The concentration of hydrogen ions in moles per liter (M) is 
Step-by-step explanation:
As we know
The hydrogen ion concentration of any solution at pH is given by

Substituting the given values in above equation, we get -
mol/l
The concentration of hydrogen ions in moles per liter (M) is 
Answer:
x=49
Step-by-step explanation:
Answer: 36.
Solve in order of PEMDAS - parentheses, exponents, multiplication, division, addition and subtraction. 21/7= 3. 3^3 is 3*3*3=27. 3+ 6 + 27= 36.