Amir is starting a stamp collection. After 3 weeks he has collected 35 different stamps, and after 9 weeks he has collected 105 different stamps. Which equation represents this direct variation?

6y=70x or 6y-70x=0;

Step-by-step explanation:

System of equations:

35=3k+b；  

105=9k+b;

Equation 2 minus 1 is 6k is equal to 70, k is equal to 70/6, plug in to equation 1 and b is equal to 0, so the original equation is y is equal to 70/6x.

(0,-3) see attached graph

step-by-step explanation:

a. to solve the system, graph the two equations.

x = y+3 becomes y=x-3 has m=1/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move up 1 unit and 1 unit to the right. plot a point and connect.

y=-4x+3 has m =-4/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move down four units and to the right 1 unit. plot a point and connect.

the solution is the point (x,y) where the two lines intersect. by the graph below it is (0,-3).

b. to solve by substitution, substitute y = -4x-3 into x= y+3

x= (-4x-3) +3

x=-4x

5x=0

x=0

now substitute x = 0 back in to find y.

y= -4(0)-3

y=0-3

y=-3

solution is (0,-3)

c. use elimination by adding the equations together.

x-y=3

4x+y=-3

5x=0

x=0

then substitute into one equation to find y.

y=-4(0)-3

y=-3