System of equations subtraction method
In the addition/subtraction method, the two equations in the system are added or subtracted to create a new equation with only one variable. ... Substitute the variable back into one of the equations and solve for the other variable. Check the solution--it should satisfy both equations.
You just keep multiplying,preferably with a calculator
Answer:
The ratio of female-to-male is 1:2
Step-by-step explanation:
There are 10 female students and 20 male students. If we were to divide each number by 10, we would get 1 and 2, respectively. That means for every 1 female student, there are 2 male students. The ratio would then be 1:2.
There are 10 letters in the set {a, b, c, d, e, f, g, h, i, j} which is the pool of letters to choose from when making these three letter codes.
We have 10 choices for slot 1
Then 9 choices for slot 2. This is because we can't reuse the choice for slot 1
Then 8 choices for slot 3
Overall, there are 10*9*8 = 90*8 = 720 different permutations
Answer: 720
Note: you can use the nPr permutation formula with n = 10 and r = 3 to get the same answer
