20. Given f(x) = 2x + 9, if f(x) = 15, find x.

The value of x if f(x) = 15 in the given function is 3

From the question,

We were given the function f(x) = 2x + 9

To determine the value of x if f(x) = 15, we will put f(x) to be equals to 15 and then solve for x in the equation

That is,

f(x) = 2x + 9

Since f(x) = 15

∴ 15 = 2x + 9

Now, to solve the above equation,

First, subtract 9 from both sides

That is,

15 - 9 = 2x +9 -9

6 = 2x

Then, we can write that

2x = 6

∴ x = 6 ÷ 2

x = 3

Hence, the value of x if f(x) = 15 in the given function is 3

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the answer is located in the screenshot that is attached.

Step-by-step explanation:

The work is also in the screenshot attached. Hoped this helped!

mr. flanders’ class sold 47 doughnuts and   mr. rodriquez’s class sold 38 cartons of milk

step-by-step explanation:

let x be the number of doughnuts sold by mr. flanders’ class and y be the number of cartons sold by mr. rodriquez’s class.

1. together, the classes sold 85 items, then

x+y=85.

2. both classes earn earned $104.49 for their school. if doughnuts were sold for $1.35 each, then x doughnuts costed $1.35x. if cartons of milk were sold for $1.08 each, then y cartons costed $1.08y. hence,

1.35x+1.08y=104.49.

3. solve the system of two equations: