Niger and Congo are two rivers after which countries are named (actually in both cases two countries each) - and those are African countries, so they must be in Africa.
Zambezi is a river in Angola and Namibia.
Tigris is a River in Mesopotamia, in Asia - so that's the correct answer!
To answer this item, we let x be the number that is not unknown in this item such that the situation in this problem can be expressed as follows,
x - 9.3 = 68.91
Adding 9.3 to both sides of the equation,
x - 9.3 + 9.3 = 68.91 + 9.3
Simplifying,
x = 78.21
The answer to this item is 78.21, this I think is the first choice except that it is mistakenly written as 7.21 only.
Here are some sources of ocean pollution:
<span>Oil. Petroleum products used for fuel are mined from the earth deep below the ocean surfaces.
Dumping.
Sewage.
Air Pollution.
<span>Agricultural Runoff</span></span>
Advantages of Free Trade:
The advocates of free trade put forward the following advantages of free trade:
(a) International Specialization:
Free trade causes international specialisation as it enables the different countries to produce those goods in which they have comparative advantage. International trade enables countries to obtain the advantages of specialisation. First, a great variety of products may be obtained.