Answer:
2 miles
Step-by-step explanation:
Their combined speed (speed of closure) is 80 mph + 40 mph = 120 mph.
120 mi/h = 120 mi/(60 min) = 2 mi/min
The distance between the trains at the 1-minute mark is ...
(1 min) · (2 mi/min) = 2 mi
They were warned when two miles apart.
Given that the line passes through the two points (-3,4) and (2,8)
We need to determine the equation of the line.
<u>Slope:</u>
The slope of the line can be determined using the formula,

Substituting the points (-3,4) and (2,8) in the above formula, we get;


Thus, the slope of the line is 
<u>Equation of the line:</u>
The equation of the line can be determined using the formula,

Substituting the point (-3,4) and
in the above formula, we have;




Thus, the equation of the line is 
Answer:
1 and 6/35
Step-by-step explanation:
You would want to multiply the denominators with the same number.
5×7
Multiply the numerators as well.
3×7 and 4×5
The fractions you would have now is 21/35 and 20/35, you can now add them up without having difficulties if the denominator is the same number.
You can also change it into decimals but I suggest this strategy.
2a + 21 = 8a - 9
Combine like terms.
2a + 21 = 8a - 9
-2a -2a
21 = 6a - 9
+9 +9
30 = 6a
6a/6 = 30/6
a = 5
Answer: a = 5