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

13

step-by-step explanation:

169-1=168

168-3=165

165-5=160

160-7=153

153-9=144

144-11=133

133-13=120

120-15=105

105-17=88

88-19=69

69-21=48

48-23=25

25-25=0

since it took 13times to completely subtract it hence its square root is 13

4 and 5)16.97 or 12√2

6)15.59 or 9√3

7)y = 15.59 or 9√3     x =27

8)17.80