Assuming that Lea has X pencils and Y colored pens, the math problem translates into the following system of linear equations:
In canonical form:
Adding both equation results in:
2X=20, therefore X=10.
Correspondingly, Y = X+8 = 18
The answer is: 10 pencils and 18 colored pens.
You may also check the answer by using online system equation solver: http://examn8.com/SystemOfEquations.aspx