Answer:
1.15b
b + 0.15b
b + (15/100)b
Step-by-step explanation:
Since the question asks for the equation that represents the pay plus the tip, which is 15% of the bill, your only answer choices are:
1.15b
b + 0.15b
b + (15/100)b
Why?
Ok, <em>b </em>is the bill in dollars. If I have to pay 15 dollars and I tip 15% of that, then I should be paying more than 15 dollars. In this example I gave, <em>b </em>is 15 dollars.
15% of b can be expressed in two ways (there's more but for now) : 0.15b or (15/100)b
15/100 is a fraction, which in decimal form is 0.15, so they are both exactly the same.
So, paying 15 dollars + 15% of the 15 will be 17.25.
Now, let's plug 15 dollars from our example in the answer choices to verify they are correct
<em>b = 15</em>
1.15b == 17.25
1.15(15) == 17.25
17.25 == 17.25 Correct
b + 0.15b == 17.25
15 + 0.15(15) == 17.25
15 + 2.25 == 17.25
17.25 == 17.25
<em>There is another way of doing the above.</em>
b + 0.15b == 17.25 # Combine like terms.
1.15b == 17.25
And then, b + (15/100)b is the same as b + 0.15b which is the same as 1.15b
Now, let's see what happens if we did a wrong one.
b + 0.15 <-- This one we expect <em>b </em>which is 15 and adding .15 cents no matter the cost
15 + 0.15 == 17.25
15.15 ≠ 17.25
1.015b <-- 0.015 in percent form is 1.5% not 15%.
1.015(15) == 17.25
15.225 ≠ 17.25
15b <-- We are multiplying b by 15. You better know your math otherwise you might pay 15x what you were supposed to pay!
15(15) == 17.25
225 ≠ 17.25
If you want to test out your equations, replace the variable; whether it is x, y, z, a, b, c - they are placeholders. Replace the placeholder with real values or equations (you will experience later).
