Answer : The equation could you use to find p is, 
Step-by-step explanation :
Let the cost of 1 pen be, 'x'
and the cost of 1 pencil is, 'p'
As we are given that total cost of 1 pen and 1 pencil is $2.10. The equation will be:
............(1)
And we have also given that the pen costs twice as much as a pencil. The equation will be:
............(2)
Now put the equation 2 in equation 1, we get:


Thus, the equation could you use to find p is, 
They have the same slope. All three lines are parallel. Any parallel lines have equal slopes.
Answer:
6 cm
Step-by-step explanation:
The diameter is 2x the radius
Answer:
0, 5
Step-by-step explanation:
I am not shure that is right but I think an ordered pair is form of a funtion.
Answer: X=17
Step-by-step explanation: (sorry if im wrong) so basicly X would be 17 because 6+2=8 so X has to +2 to get to 19 making X=17