Hey there,
#1 is D: 18 men and 30 women. The equation is: 12*m=48
#2 is B: Kathy drove 9 hours and Brain drove 3 hours. The equation is: 65m+55m/12=750
#3 is C: $0.86. The equation is: 2b+1h+1b+2h=8.52
#4 is B : 25 pizzas and 80 sodas. The equation is: 3*4p+5=260
:)
PEMDAS. parenthesis, exponents, multiple or divide (whichever come first from left to right), add or subtract (whichever comes first from left to right)
So first do stuff in parenthesis.
Then do divide because thats next on the list and it happens earlier than the multiply one.
So, A
There are 20 miles is Sheng from his home.
Add 165 to 245. That is a total of 410kWh.
245kWh is more than 50% of 410kWh.
So, according to the plan, you will pay NightTimer rate for kWh at night and DayTimer rate during the day.
The work done:

The raw, accurate, answer is that the value to pay is $22.08085.
In real terms, it is closer to your $22.08 option. That is the one I'd take.
X-intercepts
f(x) = 0
4x² - 15x - 4 = 0
4x² - 16x + x - 4 = 0
4x(x - 4) + 1(x - 4) = 0
(x - 4)(4x + 1) = 0 ⇔ x - 4 = 0 or 4x + 1 = 0
x = 4 or 4x = - 1 ⇒ x = - 1/4
Answer: -1/4 and 4.