Writing Expressions:
These key words will help you with word problems:


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+ (add, more than, increased by, sum, exceeds, gain, total, in all, plus.)
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- (subtract, difference, less than, decreased by, minus, subtracted from, reduced by.)
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x (times, multiplied, product, of, twice, triple, double.)
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/ (divided by, quotient, ratio.)
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exponent (raised to, times itself, squared, cubed.)
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example:

1) what is the quotient of 6 and 3?
2) what is the sum of 900 and 34?
3) f less than 9?

The answers- 
1) 6 / 3 = 2 
2) 900 + 34 = 934
3) 9 - f

I hope you understood this. If not, please leave me a comment!
Thanks!

-Joel