Water and wastewater · Worked step by step
What is the area of a 30 by 15 foot basin?
If math has never been your thing, you are in the right place. Try it on paper first, then we write it out with you, one small step at a time, and explain every step in plain words so you never lose the thread.
The problem
A rectangular basin is 30 feet long and 15 feet wide. What is its area?
Grab a pen and paper first
Give it a real try on paper before you watch. If you get stuck, take a hint. If you go blank, that is fine, press play and we will walk it through together.
Watch it solved, with you
Every step is written out slowly and explained in plain words, so you always know what just happened. Nobody skips ahead and leaves you behind.
Press play and I’ll write it out with you, one small step at a time.
Every step gets a plain-words explanation here, so you always know exactly what just happened and why.
The written version, step by step
- 1
Write the two sides
length = 30 ft • width = 15 ft
- A rectangle needs just its two sides.
- Length 30, width 15, both in feet.
- Nothing to convert.
- 2
Multiply length by width
area = 30 × 15 • area = 450 sq ft
- Area is length times width.
- 30 × 15 = 450.
- So the area is 450 square feet.
Quick trick: 30 × 15 is 30 × 10 (=300) plus 30 × 5 (=150), which is 450.
Remember this for good
The area of a rectangle is length times width, in square feet.
Cover the floor with 1-foot tiles: 30 along, 15 across, 30 times 15 tiles. That count is the area in square feet.
Solve it fast next time
- Rectangle area = length times width.
- Answer is in square feet.
- This is the first step of most basin volume and loading problems.
The answer: 450 square feet.