All you have to do is subtract the biggest numbers i the problems.
Let x = cost of one cheese pizza.
Let y = cost of one pepperoni pizza.
Set up a system of equations.
6x + 7y = 153.50
2x + 2y = 47.00.
Multiply the second equation by -3
6x + 7y = 153.50
-6x - 6y = -141.00.
Add the equations together
y = $12.00.
Plug 12 into one of our original equations.
2x + 2(12) = 47.
Simplify the left side.
2x + 24 = 47.
Subtract 24 from each side.
2x = 23.
Divide each side by 2
x = $11.50
In conclusion, one pepperoni pizza costs $12.00
Answer:
<em>19800 seconds, or 330 minutes, or 5 hours + 30 minutes</em>
Step-by-step explanation:
<u>Number Permutations</u>
We know the phone number has 7 digits, 4 of which are known by Mark. This leaves him 3 digits to guess with. We also know the last one is not zero. The number can be represented as
XXY
Where X can be any digit from 0 to 9 and Y can be any digit from 1 to 9. The first two can be combined in 10x10 ways, and the last one can be of 9 ways, this gives us 10x10x9 = 900 possible permutations.
If each possible number takes him 22 seconds, every possibility will need
22x900=19800 seconds, or 330 minutes, or 5 hours + 30 minutes
