Question

The temperature of the pool water started at 82 degrees, and it is cooling down 0.4 degrees each hour. If the water temperature is now 78 degrees, then how many hours have passed?

Answer 1

Answer:

We have the same homework!!!!

hours that passed= 10

Step-by-step explanation:

(1st step)We start with the expression:

(1st)82-0.4x=78

"STARTED at 82 degrees" 82

"Cooling DOWN 0.4 degrees" -0.4

"EACH hour" x

"NOW 78 degrees" =78

(2nd step) We want to get the variable x alone, so we have to do the opposite sign they have, to cancel the number out for it to be 0.

(1st) 82 -0.4x =78

(2nd) -82 ÷-0.4 =78

(3rd)Now, you work out the problem (transfer the numbers from the left to the right). First, you have to do the subtraction sign, not sure why.

(1st) 82 -0.4x =78

(2nd) -82 ÷-0.4 =78

(3rd) 78 -82= -4

-4÷-0.4= 10

X= 10

there you have it!

To make sure this is correct, you do the following.

82 -0.4 x 10

Solve using PEMDAS

-0.4 x 10 = -4

its time to add 82.

82 - 4 = 78

78 is the exact temperature that was said in the problem