Answer:
Solve for the first variable in one of the equations, then substitute the result into the other equation.
Point Form:(30/19,2/19)
Equation Form: x=30/19, y=2/19
Answer:
78.75
Step-by-step explanation:
75% of 45 is 33.75
45+33.75 = 78.75
The confidence interval would be

.
We use the formula

, where

, with p being the sample proportion and N being the sample size.
First we find the z-score associated with this level of confidence:
Convert 95% to a decimal: 95/100 = 0.95
Subtract from 1: 1-0.95 = 0.05
Divide by 2: 0.05/2 = 0.025
Subtract from 1: 1-0.025 = 0.975
Using a z-table (http://www.z-table.com) we see that this value is associated with a z-score of 1.96.
Since 578/720 said yes, this gives us p=0.80:

This gives us