Given :
a restaurant customer left a $1.95 as a tip.
The tax = 5%
the tip was 15% of the after-tax cost
So, the information that not needed is the tax
Let the total bill = x
so, 15% of x = 1.95
so, the total bill = $13
The additive inverse of 5 modulo 8 is the number a such that
5 + a ≡ 0 (mod 8)
Then
a ≡ -5 ≡ -5 + 8 ≡ 3 (mod 8)
The multiplicative inverse is m such that
5m ≡ 1 (mod 8)
Use the Euclidean algorithm:
8 = 1•5 + 3
5 = 1•3 + 2
3 = 1•2 + 1
Then
1 = 3 - 1•2
1 = 3 - 1•(5 - 1•3) = 2•3 - 1•5
1 = 2•(8 - 1•5) - 1•5 = 2•8 - 3•5
and so
1 ≡ 2•8 - 3•5 ≡ (-3)•5 (mod 8)
which means the inverse of 5 is
-3 ≡ 8 - 3 ≡ 5 (mod 8)
Answer:
80x-460=300
80x=760
Step-by-step explanation:
In order to know which equation is best, you have to add the total expenses the robotics club had.
<u>Expenses:</u>
- box of shirts = $400
- advertising = $60
Let's add: $400 + $60 =<em> $460 </em>
Next, you have to know how many of the shirts were purchased.
Now, let's compute.
- 80x - 460 = 300
- 80x = 300 + 460
- 80x = 760
- x = $9.5
or
- 80x=760
- x = 760 ÷ 80
- x = $9.5
This means that the robotics club has to sell the shirts at $9.5 each in order to have a $300 profit.