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

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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

b. 1.25 hr

step-by-step explanation:

if you have a constant speed of 60 mph, then you have a ratio between 60 mi. to 1 hr. dividing both sides by 60 we get the ratio

1 mi. to

then mult. both sides by 75 we get the ratio

75 mi. to

simplifying we get

75 mi. to

or 1.25 hr.

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.