Answer:
4
Step-by-step explanation:
Proportionality between skein values
8:2=4:1
Proportionality between cost values
28:7=4:1
The variation(both the skein values and cost values) has the constant of 4 ie the 1st skein value × 4= the last skein value & the 1st cost value × 4=the last cost value
Answer:

Step-by-step explanation:
Given the equation

Note that

and

Combined, 
Solve the equation:

Since
this is the solution to the equation.
My answer would be to add 3 to both sides
Use elimination.
-x = -6
X = 6
-4 (6) + 4y = 12
Y = 9
(X,y)
(6,9) is the solution