Solve by Element List Regression
Mixture Problem with Percentages on the SAT: Desmos Walkthrough
Let Desmos do the percent arithmetic on a single line: type the subtraction and read the result.
This lesson uses sliders and direct evaluation in Desmos: put the unknown constant on a slider or a single expression line and let the calculator find the value instead of solving algebra by hand.
Take this lesson interactivelyA real SAT-style question
The expression represents the result of decreasing a positive quantity by what percent?
A
B
C
D
How to solve it in Desmos, step by step
The idea
Since 0.35x keeps 0.35 (that is 35 percent) of x, the part removed is 1 minus 0.35. Let Desmos do that subtraction and read the decrease.
- 1
Step 1
Click an empty row in the Desmos expression list and type the subtraction below. Desmos evaluates it and shows the result equals 0.65 next to the row.Type in Desmos
- 2
Step 2
Read the result Desmos shows, which is 0.65. That equals 65 percent, so the quantity was decreased by 65 percent. The answer is D, 65 percent.
The answer is D.
Now you try one
Same question type, different numbers. Use the exact Desmos moves from the walkthrough above.
The expression represents the result of decreasing a positive quantity by what percent?
Practice this with a live Desmos calculator
The interactive version of this lesson builds the Desmos graph up step by step as you click through, with a live calculator you can type into and your progress saved.
Open the interactive lessonMore Desmos SAT lessons
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