Answer:
y=3x-15
Step-by-step explanation:
y-y1=m(x-x1)
y-9=3(x-8)
y=3x-24+9
y=3x-15
Their distance differs by 15 miles for each hour of travel time. Thus, the travel time of interest is
.. (180 -144) miles/(15 miles/hour) = 2.4 hour
The red car's speed is 180 mi/(2.4 h) = 75 mi/h.
The blue car's speed is 144 mi/(2.4 h) = 60 mi/h.
A+30 = 60
a = 30
a + 2b = 60
30+2b = 60
2b = 30
b = 15
5b - 5c = 60
5(15) - 5c = 60
5c = 15
c = 3
10c + d = 60
10(3) + d = 60
30 + d = 60
d = 30
2d + 6e = 180 - 60
2(30) + 6e = 120
6e = 60
e = 10
4f + 4e = 120
4f + 4(10) = 120
4f = 80
f = 20
You add two equations together to eliminate a variable. This particular problem is nice, because it's already setup to eliminate X.
3x - 4y = 9
<span>-3x + 2y = 9
</span>
When we add these two together, 3x - 3x cancels each other out, leaving us with 0x, or nothing.
We continue with -4y + 2y (leaves us with -2y) and 9+9 (18).
-2y = 18
18/-2 = -9.
Now we have y = -9, and we can go back into the problems to solve for x.
<span>3x - 4(-9) = 9
</span>
3x + 36 = 9.
3x = -27
x = -9.
Confirm with the final equation:
-3(-9) + 2(-9) = 9
27 - 18 = 9
9 = 9 --- Confirmed.
