220=A+S (adult plus student)
s=220-a
2.50a+1.50s=465
1.50s=-2.50a+465
s=-1.67a+310
then set those equal to each other
220-a=-1.67a+310
220=-.67a+310
-90=-.67a
.67a=90
a=60
then put a back into the first equation
220=S+A
220=s+60
s=160
a=60, s=160
when you are adding two negative numbers, the sum is basically the two numbers added together but as a negative. when added together they create a larger negative number; ex. -2 -8 = -10 which is the same as 2 + -8 = -10. when you are multiplying two negative numbers, you are really just multiplying the numbers and they come out to be a positive. a negative times a negative is a positive. ex. -5 x -5 = 25.
43n^2-54. then do the exponent part your self! :)
A) 276 / 138 = 2
B) 26/2 = 13, 13/2 = 6.5
Answer is B