80+10x is the expression. To find the cost for 9 guests, simply plug in 9 for x. This becomes an equation reading 80+10(9)=170. The total cost for 9 guests is $170.00.
The final price is the cost plus the tax.
Since we know the tax and a percent, we can write this as
T = C(1+r)
T = what Graham paid = $87.45
C = cost before tax
r = tax rate expressed as a decimal = .40
Plugging in what we know
87.45 = C (1+.4)
87.45 = C(1.4)
Divide both sides by 1.4
C = $62.46
25-4x=16-4x
25-4x+4x=16-4x+4x
25=16
No solution
Contradiction
Step-by-step explanation:
I don't know if the first set of numbers is all in one set, but I'll do my best to give you an answer.
Really all you need to do is use PEMDAS for the first question.
(Parentheses, exponents, multiply, divide, add, subtract. In that order)

Then to simplify that fraction next to it, notice that 0.018 is 3x 0.06.
that's a 3:1 ratio, so it ends up simplifying to this:

Lastly, to solve the division of that fraction. If you divide by a fraction, you multiply whatever it's dividing by its inverse.
So...

To find the equation, we first need to change the unit as you did correctly:
1 feet = 12 inches
In this case,let's turn the unit of depth to feet:
4÷12
= 1/3 feet
Then we can find the volume in inches:
1/3×162×6
=54×6
=324 ft^3
Therefore the answer is B.324 ft^3 .
Hope it helps!