Mr. Bower has 3 times as many pens as pencils. He has 20 pens and pencils altogether. How many pens does he have?
Solve by trial and error:
Say you have 1 pencil, then you have 3 pens ( 3 times 1 = 3)
1 + 3 = 4, so you don't get 20
Say you have 3 pencils, then you have 9 pens ( 3 times 3 = 9 )
3 + 9 = 12, so you don't get 20
Say you have 4 pencils, then you have 12 pens ( 3 times 4 = 12 )
4 + 12 = 16, so you don't get 20
Say you have 5 pencils, then you have 15 pens ( 3 times 5 = 15)
Since 5 + 15 = 20, then you have 5 pencils and 15 pens.
May 21, 18 09:24 AM
Explore exponential and logarithmic functions with these easy to follow math lessons
New math lessons
Your email is safe with us. We will only use it to inform you about new math lessons.
May 21, 18 09:24 AM
Explore exponential and logarithmic functions with these easy to follow math lessons
Our Top Pages
Formula for percentage
Compatible numbers
Basic math test
Basic math formulas
Types of angles
Math problem solver
Algebra word problems
Surface area of a cube
Finding the average
Scale drawings
Everything you need to prepare for an important exam!
K-12 tests, GED math test, basic math tests, geometry tests, algebra tests.
Real Life Math Skills
Learn about investing money, budgeting your money, paying taxes, mortgage loans, and even the math involved in playing baseball.