1)combine like terms
2) move 9 to the other side by subtracting 9
3) divide by the # that is in front of y - to both sides
answer you should get: -11/2
Total amount of trail mix which is poured into the bags =
pounds
=
pounds
Total amount of trail mix in each bag =
pound
Number of bags with
pound, which can be poured from
pounds of trail mix
= Total amount of trail mix
Amount of trail mix in each bag
= 
= 
= 6 bags
Number of bags taken on a hiking trip =
of bags
= 
= 4 bags
Now, number of bags of trail mix which are left = 6-4 = 2 bags.
Therefore, 2 bags are left.
Theoretical probability is what u expect to happen...although it might not happen that way. The theoretical probability of spinning a coin 100 times and it landing on heads is 50%...and 50% of 100 = 50....so would expect it to and on heads 50 times.
The experimental probability is what actually happens...the experimental probability when spinning a coin 100 times and it landing on heads 38 of those times = 38/100 = 0.38 = 38%
You can use Euler's Polyherdron Formula as seen here;
https://plus.maths.org/content/eulers-polyhedron-formula
The number of vertices minus the number of edges plus the number of Faces will equal 2.
V - E + F = 2
V - 36 + 25 = 2
V = 13