other words you should know:
"difference" means "subtract"
example, what is the difference between 8 and 3?
difference = 8 - 3 = 5
"product" means "multiply"
example, what is the product of 4 and 2?
product = 4*2 = 8
"percent" means "/100" or "out of 100"
example, write 15% as a fraction:
15% = 15/100 = 3/20
example 2, write 15% as a decimal
15% = 15/100 = 0.15
"of" also means "multiply"
example, what is 15% of 200?
15% of 200 = 15/100 * 200 = 3/20 * 200 = 30