Question

1. the expression $-120 + 13m$ represents a submarine that began at a depth of 120 feet below sea level and ascended at a rate of 13 feet per minute. what was the depth of the submarine after 6 minutes?18. be precise a full grain silo empties at a constant rate. write an expression to determine the amount of grain left after $s$ seconds.rate: $3.5\\ \text{ft}^3/\text{h}$19. higher order thinking for the expression $5 - 5x$ to have a negative value, what must be true about the value of $x$?assessment practice20. joe bought $g$ gallons of gasoline for $\\$2.85$ per gallon and $c$ cans of oil for $\\$3.15$ per can.part awhat expression can be used to determine the total amount joe spent on gasoline and oil?part bjoe spent $\\$15$. he bought 2 cans of oil. about how many gallons of gasoline did he buy?a 2.5b 3c 3.5d 421. the outside temperature was $73^\circ\text{f}$ at 1 p.m. and decreases at a rate of $1.5^\circ\text{f}$ each hour. what expression can be used to determine the temperature $h$ hours after 1 p.m.?

Explanation:

Problem 17

Step1: Substitute m=6 into expression

$\text{Depth} = -120 + 13(6)$

Step2: Calculate the product first

$13(6) = 78$

Step3: Compute final depth

$-120 + 78 = -42$

Step1: Convert rate to ft³ per second

First, convert hours to seconds: 1 hour = 3600 seconds.
$\text{Rate per second} = \frac{3.5}{3600}$

Step2: Define initial grain as $V$ (full silo)

Let $V$ = total volume of the full silo.

Step3: Write expression for remaining grain

$\text{Grain left} = V - \frac{3.5}{3600}s$

Step1: Set expression less than 0

$5 - 5x < 0$

Step2: Isolate the term with $x$

$-5x < -5$

Step3: Solve for $x$ (reverse inequality)

$x > 1$

Answer:

The depth of the submarine after 6 minutes is -42 feet (42 feet below sea level).

---

Problem 18