Hi there,
Your question is "twice a number (x) is fifty"
Recall how a number is represented by x.
Twice a number would be represented as 2x.
Therefore, to represent that twice a number is equal to 50, that would result in the expression: 
If you're looking to solve this equation, it's often best to think about the "reverse" of the current equation.
Notice how 2 is multiplying the x.
To isolate x, divide that side by 2.
However, recall that whatever is done to one side of an equation must also be done to the other side of the equation. Therefore, you will need to divide both sides by 2.



Equation: 
Solving for x: 25
Hope that helps!
Answer:
(96.91, 101.09)
Step-by-step explanation:
To calculate the interval, you require the Z value at 95% confidence interval. The Z value is 1.96. The formula to calculate the confidence interval:

Where X is the mean and s is the standard deviation and x the sample size:

The interval is (96.91, 101.09)
Since a cm is 1/100th of a meter, 43 cm would simply be 43/100. Hope that helps!
Measures of angles 2, 3, 4, added equal 180