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### Course: Digital SAT Math>Unit 2

Lesson 6: Systems of linear equations word problems: foundations

# Systems of linear equations word problems — Harder example

Watch Sal work through a harder Systems of linear equations word problem.

## Want to join the conversation?

• you can solve it with less time and effort. you can substract 4 children and 1 adult from each choice and see if the remaining children are double the adults since each of the remaining adults brought 2 children. think smarter not harder haha
• Agnes has 23 collectible stones, all of which are labradorite crystals or galena crystals. Labradorite crystals are worth \$20 each, while galena crystals are worth \$13 each. Agnes earns \$439 by selling her entire collection. How many stones of each type did she sell?

• 20 labradorite and 3 galena
because 20*20=400 and 3*13=39 so the total will be 439 which is exactly how much Agnes made
• good concept but a little bit confusing
• That was a tricky one!
• Right do you need help>
(1 vote)
• My solution:

Consider the number of adults to be x
Subsequently, the number of children can be written in terms of x as "2x + 2". (Each adult brings 2 children and one of the adults brought 2 extra children)

Now multiply the number of adults and children with their corresponding prices and equate that to 60.
That is "2(2x + 2) + 4x = 60"

Upon solving, you shall get x = 7 which implies that there are 7 adults. Thereafter, you can also find out the number of children which is "2x + 2" and that is 16. Thus, Option C is correct.
• Why are we given harder practice problems then what the example shows? This one looks more simple, but the other practice problems are so complicated sometimes. The SAT is coming soon, I just feel so under prepared..
• exactly. this is why i find these videos ineffective sometimes. i wish the exercises had the same difficulty level as the videos
• Here's my solution:

4+2(a-1)=c
4+2a-2=c
2a+2=c

2(2a+2)+4a=60
4a+4+4a=60
8a=56
a=7

*Note: a-1 = number of children who brought 2 children
subtract the one who brought 4
• A lil confusing