What are the quick methods to solve percentage equations?

Get a ruler in your hands. Measure things until you start to understand how a ruler works. Measure some stuff and figure out where the center is. Say you measure a book and it's 7/8" thick. You look at your ruler and see that every eighth is divided into two sixteenths, so obviously half of 7/8" is going to be 7/16". If you write that out you have 1/2 x 7/8 = 7/16. And you notice that 1/2 is divided into 2/4 and then into 4/8 and so on, so you can convert anything to anything by multiplying all the numbers on top and then all the numbers on bottom.

Other rulers are divided into 10 and 100 parts. But an inch is still an inch, so anything on one ruler can be translated to the other ruler. A half inch on one ruler is 5/10 or 50/100 on the other. An eighth inch is just 12.5 marks when you have 100 marks per inch. A metric ruler divides an inch into 25.4 parts, so a half inch would be 12.7 of those parts. Pretty simple, isn't it? Practice this a bit and people will think you went to wizard school.

Percent is simply a ruler with 100 marks. The only confusion is trying to keep track of what the marks represent, since that changes from time to time.

I started to answer your question earlier with "Convert the percent to decimals. This will be easier if you are familiar with the American dollar. Think of 1% as one hundreth 1/100 of anything.
A dollar has one hundred pennies.
One penny is 1 hundreth of a dollar, or 1% of a dollar, or $0.01
25 cents is 1/4 (one quarter) of a dollar, or .25 (25% of a dollar)

So, to convert a percentage to a decimal,

16% of 100 = 100 x .16
That means that 16% of 100 pennies in a dollar is 16 pennies

One half of a dollar is 50 pennies, so 16% of 50 =
50 x .16 = 8

Simplified

To convert a pecentage to decimals,
10% of 100 means .10 x 100
25% of 100 means .25 x 100

60% of 1200 + 90% of 180
1200 x .60 + 180 x .90

Simplified further
To convert a percentage to a decimal,
55% = .55

There are percentage calculators available online.