a map is drawn using a scale of 1cm/80mi . two cities are 280 miles apart.how far apart are the cities on the map

3.5 cm

Step-by-step explanation:

Use a proportion.

280 miles is to 80 miles as x cm is to 1 cm

280/80 = x/1

28/8 = x/1

8x = 28

x = 3.5

3.5 cm

D) f(n) = 3 + 4(n-1)

3 = 1st term
4 = common difference among the terms
n = term number you are looking for.

To check: 3, 7, 11, 15, ...

f(1) = 3 + 4(1-1) = 3 + 4(0) = 3 + 0 = 3
f(2) = 3 + 4(2-1) = 3 + 4(1) = 3 + 4 = 7
f(3) = 3 + 4(3-1) = 3 + 4(2) = 3 + 8 = 11
f(4) = 3 + 4(4-1) = 3 + 4(3) = 3 + 12 = 15