It looks like the differential equation is

Check for exactness:

As is, the DE is not exact, so let's try to find an integrating factor <em>µ(x, y)</em> such that

*is* exact. If this modified DE is exact, then

We have

Notice that if we let <em>µ(x, y)</em> = <em>µ(x)</em> be independent of <em>y</em>, then <em>∂µ/∂y</em> = 0 and we can solve for <em>µ</em> :

The modified DE,

is now exact:

So we look for a solution of the form <em>F(x, y)</em> = <em>C</em>. This solution is such that

Integrate both sides of the first condition with respect to <em>x</em> :

Differentiate both sides of this with respect to <em>y</em> :

Then the general solution to the DE is

Let's assume
the price of each train ticket is x
we are given
total number of family members =5
so, total cost of ticket = total number of family members*the price of each ticket
so, total cost of ticket =5*x
so, total cost of ticket =5x
now, we have
each family member buys a boxed lunch for $6.50
so, total cost of lunch box = total number of family members*price of each lunch box
so, total cost of lunch box = 5*6.50
total cost of trip = total cost of ticket+total cost of lunch box
we are given
total cost of trip is $248.50
now, we can plug values
and we get

now, we can solve for x





so,
the price of each train ticket is $43.2..........Answer
Subsequent means following (in time, order or place f.e.)
The slope is 0.1
To find a perpendicular slope, find the negative reciprocal.
The reciprocal of 0.1 is 10
The negative of 10 is -10
Final answer:-10