Problem 1) xy means "x times y". The multiplication symbol is left out because its implied. You can write x*y if you wish. Or we can say "product of two numbers" since a product in math terms is the result of multiplication.
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Problem 2) x/y means "x divided by y" which is a fraction
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Problem 3)
Writing "x-y" is the same as saying "x minus y"
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Problem 4)
x+y is "x plus y", or we can say "the sum of x and y". The "sum" is "result of adding two or more values"
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Problem 5)
y-x is "y minus x" or we can say "x subtracted from y"
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Problem 6)
y division symbol x is essentially the flip of problem 2. We'd say "y divided by x"
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Problem 7)
x+y = 6 is "the sum of two numbers is 6". See problem 4 above.
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Problem 8)
xy = 6 is "the product of two numbers is 6". This is an extension of problem 1.
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Problem 9)
6x = y is "six times a number equals y" when translated out
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Problem 10)
y = x-6 would translate to "six less than a number is y"
where the "a number" portion is represented by x