The percent proportion is a/b = p/100, where p is the percentage of the total fraction on the left side of the equation that you are trying to figure out.
We know that p=5, because p represents percentage, and the percentage 5% is equal to the fraction 5/100. Also, we know that 60 = b, or the denominator as this is the entire portion that we are trying to figure out.
a/60=5/100
Now, we need to use cross products, or multiplying the numerator of one fraction by the denominator of the other, and setting them equal to one another.
100 * a = 60 * 5
If we simplify by multiplying, then we get the equation:
100a = 300
When we divide the variable by the coefficient, we get the equation