In a lab, a substance was cooled by 4 C each hour for 28 hours. What was the total change in temperature?

45

step-by-step explanation:

to find a percentage, add a decimal in front and multiply it by the other number.

.25 times 180= 45

step-by-step explanation:

step 1: solve one of the equations for one of the variables. let's solve the first equation for y:

step 2: substitute that equation into the other equation, and solve for x.

step 3: substitute x = 4 x = 4 x=4 into one of the original equations, and solve for y.

it's undefined because anything multiplied by 0 is 0. that said, 7 days is 168 hours