Find factors of 12 and 21
Divide 3 from both numerator and denominator.
(12/21)/(3/3) = 4/7
4/7 is your ratio equivalent to 12/21
hope this helps
yes, I'm pretty shure they do
To get from 40% to 100%, divide by 2 and multiply by 5.
I.e. 40/2 = 20
20 x 5 = 100%
Do the exact same for 102
102/2 = 51
51 x 5 = 255 students

Above step we use "Multiplication property of equality"

In the above step we "Simplify on both sides of equation"

In the above step we use "Distribution property"

The above step is the result of using "Subtraction property of equality"

Above step is result of "Combining the like terms"

Above step is the result of using "Division property of equality"

Above step is result of "Simplifying fractions on either side of equation"