What is one way that southerners attempted to protect their ports

The evasion of the naval blockade during the Civil War was a set of operations designed to avoid the situation of blockade that the unionist side imposed on the Confederate side during the American Civil War, which stretched over 5,600 kilometers (3,500 miles) , from the Atlantic Ocean and the Gulf of Mexico, and to the Mississippi River. The evasion was carried out by means of steamships, many of them specially built to reach a high speed for the time, that had to sail normally at night to not be detected. If they were sighted, the ships (called blockade runners) tried to maneuver or simply surpass any Union ship that was acting as a blocking patrol. The boats used for this task were generally privately owned, often operating with a privateering license issued by the Confederate States of America.

the perimeter of a triangle is 69 cm. side a is 5 cm shorter than side b. side c is twice as long as side a. find the length of each side. i need to know how to do it in 2 equations.  

equations:

a = b-5

c = 2a

a + b + c = 69

the causes of the dust bowls were severe droughts,   lands became dry and hard, temperature was higher than usual, hot and dry conditions killed crops, high winds. because of those factors, the winds kicked up dry soil and created clouds of dust.