There's a linear relationship between the number of credits a community college student is enrolled for and the total registration cost. a student taking 9 credits pays $ 983 to register. a student taking 13 credits pays $ 1411 to register. let x represent the number of credits a student enrolls for and let y represent the total cost, in dollars. write an equation, in slope-intercept form, that correctly models this situation.

y = 107x + 20

Step-by-step explanation:

The points that represent the number of credits and the cost of those credits in coordinate form are (9, 983) and (13, 1411).

We can use the slope formula to first find the slope of the line containing those 2 points:

The slope is 107.  Now we can pick one of the 2 points and use it in the point-slope form of a line to get the equation we are looking for:

simplifies to

so in slope-intercept form:

y = 107x + 20

step-by-step explanation:

30% of $420 is 0.30($420) = $126 and $420 + $126 = $546.

or, 130% of $420 is 1.3($420) = $546.

notice that this is not the $600 original list price with which we started.

why doesn't this work?

the method does not work because 30% of $420 is not the same amount as the 30% of $600. it may seem obvious when stated this way, but it is a very common error made on problems of this type. we cannot just use the same percent and get back to the original amount because we are taking that percent of a different value.

to work problems of this type correctly, it is generally best to write an equation for the situation and then solve.

example: since (100% – 30%)(original price) = (sale price)

70% of the   (original price) is $420.

0.7x   = 420

equation image indicator

x = 600

the original cost was $600.

we may also solve this problem using the two-step method. working the problem in two steps requires us to use more algebra skills. we have to know that x = 1x (identity property of multiplicationtext annotation indicator) and that 1x – 0.3x = 0.7x (subtracting like terms). then we solve the problem as follows:

(original price) – 30%(original price) = sale price

x – 0.3x = 420

0.7x = $420

equation image indicator

x = 600

the original cost was $600.  

note that with both of the above methods we do obtain the correct original amount.

example: after a 5% pay raise, hermione is earning $22,680 per year. what was she earning before the pay raise?

105% of (original salary) = current salary

1.05x = 22,680

equation image indicator

x = 21,600

hermione earned $21,600 per year before the pay raise.

this is an example so maybe you will get how to at least do it!

i am currently in the exact same situation rn. algebra2/adv algebra is killing

step-by-step explanation: