Question

3 roads, a, b, and

Answer 1

3 roads...a, b and c

b = 3a.....a = 1/3b
c = 2b.....b = 1/2c.....

a ------|
b ------|--------|------|
c ------|--------|------|------|------|------|

so a is 1/6 of the total road <===

if road b is 7 miles longer the a...
b = 3a....b = a + 7
a + 7 = 3a
7 = 3a - a
7 = 2a
7/2 = a
3.5 = a

b = 3a
b = 3(3.5)
b = 10.5

c = 2b
c = 2(10.5)
c = 21 <=====road C is 21