Answer:

Step-by-step explanation:
we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form
or 
Let
c ----> the total cost of the boat rental
d ---> is the number of days, the family rents the boat
we know that
Kaya's family spends $105 to rent a boat for 7 days
so
For d=7 days, c=$105
Find the value of the constant of proportionality k

substitute the given values

therefore
The linear direct equation is equal to

Answer:
x= 2
Step-by-step explanation:
5 -2(x +5)= 3x -15
Expand:
5 -2x -2(5)= 3x -15
5 -2x -10= 3x -15
Simplify:
-2x -5= 3x -15
Bring x terms to 1 side, constant to the other:
3x +2x= 15 -5
5x= 10
Divide both sides by 5:
x= 10 ÷5
x= 2