Answer:
11.4
20/100 = x/57
Step-by-step explanation:
It is perhaps simplest just to translate the given English sentence into a mathematical sentence.
... 20% ... ... of ... 57 ... is ... what number
... 20/100 ... × ... 57 .... = ... what number . . . . . . . . translation to math sentence
... 11.4 = what number . . . . . . . . carry out the multiplication
_____
If you're asked to write this as a proportion, you can write it like this:

You can solve this proportion by multiplying by 57 (the denominator under "what number"). Doing so gives you the same arithmetic sentence as shown above.
Answer:
$13.95
Step-by-step explanation:
You need to multiply the 5 notebooks with the costs of each notebook, which gives you the total costs before tax.
Answer:
245 miles
Step-by-step explanation:
To complete this, you want to use the unit conversion technique in fraction form. The units for the numerator of the first fraction (thing you want to convert) should match the units of the denominator in the multiplying fraction.