Linear Equations Real World Problems

After paying $5.12 for a salad, Kamauri has $27.10. How much money did he have before buying the salad?

• n + $5.12 = $27.10

• n - $5.12 = $27.10

• n - $5.12 = -$27.10

• $5.12 - n = $27.10

Which equation would describe "two times a number plus five equals 15"?

• x + 5 = 15

• 2x + 5=15

• x + 2(5) = 15

• 2(x + 5) = 15

What is the first step in solving this equation:
5x + 7 = 12

• Divide by 5

• Subtract 5

• Multiply by 7

• Subtract 7

2x + 1 = 6

What would the first step be in solving this equation?

• Divide by 2

• Subtract 1

• Subtract 6

• Times 2

The Roaming Cell Phone Company charges $15.00 per month plus $0.20 per minute of airtime usage. If Juanita uses x minutes of airtime, what is an equation that can be used to determine her monthly cell phone bill? The equation is y=0.20x+15. What does the y mean?

• amount of minutes

• total cost

• cost per minute

• variable

• flat fee

Mathematical Equivalence

ON

Answer explanation

y = x + 8 | This tree is 8 feet tall and growing 1 foot each year.

y = x/2 + 10 | This tree is 10 feet tall and growing 1/2 foot each year.

Substitute x + 8 for y in 2nd equation

x + 8 = x/2 + 10

x - x/2 + 8 -8 = x/2 - x/2 + 10 -8

x/2 = 2 | x = 4 years

• $9

• $15

• $24

• $39

The cost, c, to park in a parking garage can be represented using the equation c = 5 + 0.5h, where h is the number of hours the car is in the parking garage. Which of these statements is TRUE?

• It costs $0.50 to park in the garage for 1 hour.

• It costs $5 to park in the garage for 1 hour.

• It costs $5 per hour to park in the garage.

• It costs $6 to park in the garage for 2 hours.

Joe’s Canoes charges an initial fee of $20 plus $4 an hour. Callie’s Canoes charges a flat rate of $14 an hour. Find the number of hours for which the total amount that both places charge would be the same.

• 3 hours

• 4 hours

• 1 hour

• 2 hours

Mathematical Equivalence

ON

Answer explanation

y = x + 8 | This tree is 8 feet tall and growing 1 foot each year.

y = x/2 + 10 | This tree is 10 feet tall and growing 1/2 foot each year.

Substitute x + 8 for y in 2nd equation

x + 8 = x/2 + 10

x - x/2 + 8 -8 = x/2 - x/2 + 10 -8

x/2 = 2 | x = 4 years