How far will a train travel in 5 hours if it travels at 80 miles per hour?

a. 16 miles
b. 160 miles
c. 400 miles
d. 40 miles

  C.  400 miles

Step-by-step explanation:

In each hour, it travels 80 miles. (That is the meaning of "80 miles per hour.") So you can add up the distances over a period of 5 hours:

  80 miles + 80 miles + 80 miles + 80 miles + 80 miles

After the first sum (80+80=160), you can see what the correct answer will be. Continuing, you find the sum to be ...

  = 400 miles

___

Multiplication was invented to make repeated addition easier.

  5 × 80 miles = 400 miles

Strictly speaking, you are multiplying numbers with units here:

  (5 h) × (80 mi/h) = 400 mi·h/h = 400 mi . . . . . . the units h/h cancel

x=-2

infinite number of lines, so there is an infinite number of equations.

step-by-step explanation:

there are an infinite number of line that passes through the point (-2,5)

x=-2   is one line that passes through the point

y = 5 is another line that passes through the point

(these two lines are perpendicular to each other).

since the number of   numbers are infinite and the slope is the ratio of two numbers,(change in y over change in x) we can have an infinite number of slopes.     our only condition is that it passes through the point (-2,5)

70,000 + 6,000 + 800 + 30

step-by-step explanation: