You need to understand that you're solving for the average, which you already know: 90. Since you know the values of the first three exams, and you know what your final value needs to be, just set up the problem like you would any time you're averaging something.
Solving for the average is simple:
Add up all of the exam scores and divide that number by the number of exams you took.
(87 + 88 + 92) / 3 = your average if you didn't count that fourth exam.
Since you know you have that fourth exam, just substitute it into the total value as an unknown, X:
(87 + 88 + 92 + X) / 4 = 90
Now you need to solve for X, the unknown:
87
+
88
+
92
+
X
4
(4) = 90 (4)
Multiplying for four on each side cancels out the fraction.
So now you have:
87 + 88 + 92 + X = 360
This can be simplified as:
267 + X = 360
Negating the 267 on each side will isolate the X value, and give you your final answer:
X = 93
Now that you have an answer, ask yourself, "does it make sense?"
I say that it does, because there were two tests that were below average, and one that was just slightly above average. So, it makes sense that you'd want to have a higher-ish test score on the fourth exam.
11 because -7 subtracted by 4 add kore to the 7 so think of it this way -7 is a bad guy and 4 is a bad guy to because its a subtraction so if both bad guys combine you get 11 because a negative with negative makes a positive so its 11
Easy Algebra question!
Let's use "x" as a variable.
The equation would be x+x+60 = 240 with "x" being George's weight.
Subtract 60 from both sides and you get 2x = 180.
From there you divide both sides by 2, getting x=90.
"x" is George's weight, so he weighs 90 pounds.
ANSWER: 90 POUNDS
1/2 Gallon is equal to 64 ounces
16 x 6 = 96
96 + 64 = 160
5 gallons is equal to 640
640 - 160 = 480
