Answer:
North America has 23 countries
Europe has 46 countries
Africa ha 53 countries
Step-by-step explanation:
Firstly to answer the question, we define variables. Let the number of countries in Africa be A, the number of countries in europe be E while the number of countries in North America be N.
Firstly, we are told there are a total number of 122 countries. Mathematically this means the addition of all the countries will give 122
Hence;
N + A + E = 122. •••••••(i)
Secondly we are made to know that Europe has twice as many countries as North America;
Mathematically l, this means
E = 2N. •••••••••(ii)
Thirdly we know that Africa has 7 more countries than Europe;
This mathematically means that
A = E + 7. •••••••••(iii)
Since E = 2N, A = 2N + 7 ••••••••(iv)
Now what to do to find the answer is to substitute equation ii and iv at the same time into equation i
This will give the following;
N + 2N + 2N + 7 = 122
5N = 122 - 7
5N = 115
N = 115/5
N = 23
We recall
E = 2N = 2(23) = 46
Also
A = 2N + 7 = 46 + 7 = 53
Answer: The number of countries are as follows;
North America = 23, Europe = 46 and Africa = 53
Step-by-step explanation: First of all we identify the variables as algebraic expressions. Hence let North America be N, Europe be E, and Africa be F.
So what we have is;
N + E + F = 122
If Europe has twice as many countries as North America, then Europe can be re-written as 2N. Also if Africa has seven countries more than Europe, then Africa can be re-written as 7 +2N.
Therefore the equation N + E + F = 122 can now be re-written as follows;
N + 2N + 7 + 2N = 122
5N + 7 = 122
Subtract 7 from both sides of the equation
5N = 115
Divide both sides of the equation by 5
N = 23
Hence, North America (N) = 23
Europe (E) = 46
Africa (F) = 53
