Answer:

With
representing the slope we have that:


And we are interest on this case the interpretation about the slope and we can conclude that:
For every unit increase in literacy rate (percent of the population that is literate) the age difference (husband minus wife age) falls by 0.0437 units, on average.
Step-by-step explanation:
For this case we have that the regression model adjusted between age difference (husband minus wife age) representing the y variable and literacy rate (percent of the population that is literate) representing the variable x is given by:
where 
And we know that the method used in order to adjust the regression line was least squares.
For this case our dependent variable is y = age difference (husband minus wife age) and the independent variable is x=literacy rate (percent of the population that is literate)
If we compare the regression model adjusted with the linear regression model:

With
representing the slope we have that:


And we are interest on this case the interpretation about the slope and we can conclude that:
For every unit increase in literacy rate (percent of the population that is literate) the age difference (husband minus wife age) falls by 0.0437 units, on average.
Let x be the number of adult tickets sold.
<span>That means 400 - x is the number of student tickets.
The revenue from adult tickets will be $3 * x, which we can call 3x.
The revenue from student ticks will be $2 * (400 - x), or 800 - 2x.
The total revenue is $1050, so that means:
3x + (800 - 2x) = 1050.
Removing the parentheses:
3x + 800 - 2x = 1050
</span><span>Subtracting 800 from both sides:
3x - 2x = 250
Simplifying the left side:
x = 250, which is the number of adult tickets.
400-x = student tickets = 400-250 = 150.
ALWAYS check!
In this case, check the revenue:
3x = 3(250) = 750
2(150) = 300
750 + 300 = 1050. Check!</span>
Answer:
0.04 is as close as it gets