Answer:
Since it took Juan 16 hours to wrap 2 presents, it will take Juan 32 hours.
1 present- 8 hours
2 present- 16 hours
3 present- 24 hours
4 present- 32 hours
The solution depends on the value of

. To make things simple, assume

. The homogeneous part of the equation is

and has characteristic equation

which admits the characteristic solution

.
For the solution to the nonhomogeneous equation, a reasonable guess for the particular solution might be

. Then

So you have


This means


and so the general solution would be
The answer would be an odd number, 111.
Using the law of cosines:
The grocery store to the school:
Distance = √(7^2 + 10^2 - 2*7*10*cos(100)
Distance = 13.16 miles
The movie store to the school:
Distance = √(7^2 + 10^2 - 2*7*10*cos(120)
Distance = 14.80 miles
The friend is further away.