Question 110·Medium·Linear Inequalities in One or Two Variables
At a school fundraiser, the club earns $12 for each bracelet and $20 for each hoodie sold. The club needs to raise at least $600. If is the number of bracelets and is the number of hoodies sold, which inequality represents all combinations of and that meet the fundraising goal?
For SAT word problems with inequalities, first translate each part of the story into algebra: write an expression for the total quantity (here, total money: ) by multiplying the per-item amount by the number of items and adding. Then translate key phrases precisely: “at least” means , “at most” means , “more than” means , and “less than” means . Finally, place the inequality symbol between your total expression and the target number and quickly check that larger totals are allowed or disallowed in a way that fits the wording.
Hints
Represent the total money in terms of b and h
First, write an expression for how much money comes from bracelets and another for how much comes from hoodies, then add them.
Focus on the phrase “at least $600”
Does “at least $600” mean the total money should be less than 600, more than 600, or 600 or more? Which inequality symbol matches that idea?
Form the inequality
Once you have the expression for total money and you know which direction the inequality should go, place the inequality sign between the total expression and 600.
Desmos Guide
Choose test combinations of bracelets and hoodies
Pick one combination that clearly meets the goal and one that clearly does not. For example:
- A meeting combo: 10 bracelets and 25 hoodies gives , which is at least $600.
- A non-meeting combo: 5 bracelets and 10 hoodies gives , which is less than $600.
In Desmos, plot these as points and .
Graph each answer choice as an inequality
Treat as (bracelets) and as (hoodies). For each answer choice, type the inequality exactly as written but replace with and with (for example, for choice A, type 12x + 20y <= 600). Desmos will shade the solution region for that inequality.
Check which inequality matches the situation
For each graphed inequality, see whether the point that meets the goal lies in the shaded region and the point that does not meet the goal lies outside it. The correct answer choice is the one whose shaded region includes the successful combination and excludes the unsuccessful one.
Step-by-step Explanation
Write expressions for the money from each item
Each bracelet earns $12, and there are bracelets, so the money from bracelets is .
Each hoodie earns $20, and there are hoodies, so the money from hoodies is .
Combine to get the total amount of money raised
To find the total money raised, add the money from bracelets and hoodies:
This expression represents the total dollars the club earns from selling bracelets and hoodies.
Translate “at least $600” into an inequality and match the choice
The phrase “at least $600” means the total money is 600 or more, so the total must be greater than or equal to 600. In symbols, that is written with .
So we require
This matches answer choice D) .