5 packs of stamps and 7 packs of envelopes. There will be a total of 70 envelopes and stamps.
Answer: The first option, the one in orange.
Step-by-step explanation:
This is the associative property.
Hope this helps, good luck on the test! :)

Rounding to nearest thousand gives 76,000 mg of chlorine
The answer would be -3/2
A reciprocal is the inverse of a number.
When using this in fractions just switch the numerator and denominator. This is done by dividing the fraction by one, but in the case of a negative fraction you would divide by negative 1.