Write x and y down separated by a colon, as in "x:y," on lined paper. This is the standard way that ratios are written.
Skip a line and write the value x, a line under it and then the y value under the line. This notation signifies x divided by y.
Enter the x value into a calculator, press the divide symbol ("÷"), enter the y value and press the equals button ("="). This value is the ratio of x and y.
Skip a line on the paper, write an equals sign and write the number on the calculator screen.
Multiply the value by 100 to transform the ratio of x to y into a percentage. This will give you the size of x as a percentage of y.
Write the equation, such as y = 2x - 4. In this equation the slope of the line is the coefficient of x, 2, and the y-intercept is 4. The intercept is the point at which this linear equation would cross the y-axis if drawn on a graph. The slope stays constant, unlike the ratio of x/y, which changes depending on the values of x and y. This is because of the presence of the intercept.
Skip a line and rearrange the equation so that the x term alone is on one side:
y + 4 = 2x
Divide all of the terms on both sides by y to achieve the form x/y:
1 + 4/y = 2x/y
Divide both sides by 2 to get the ratio of x to y.
1/2 + 2/y = x/y
Enter an x value into the original equation. For example, plug in x = 3:
y = 2x - 4 = 6 - 4
y = 2
Enter the y value into the equation to find the ratio of x to y when x is 3 and y is 2.
x/y = 1/2 + 2/y
= 1/2 + 1
= 1 and 1/2, or 3/2