7.The mass of a grain of sand is approximately 2.8×10^−11 grams
2 answers:
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Answer:
Step-by-step explanation:
The correct question is
Susan works as a tutor for $10 and hour, and as a waitress for $11 an hour. This month, she worked a combined total of 90 hours at her two jobs. Let t be the number of hours Susan worked as a tutor this month. Write an expression for the combined total dollar amount she earned this month
Let
t -----> the number of hours that Susan work as a tutor
y ----> the number of hours that Susan work as a waitress
z ---> the combined total dollar amount she earned this month
we know that
-----> equation A
we know that
The combined total dollar amount she earned this month is equal to the number of hours that Susan work as a tutor multiplied by $10 plus the number of hours that Susan work as a waitress multiplied by $11
----> equation B
substitute equation A in equation B
therefore
The expression for the combined total dollar amount is $(990-t)
Answer:
a. 4 : 1
b. 2 students
c. 3 : 1
Step-by-step explanation:
a. There were 12 students who got a C and 3 students who got As. The ratio is therefore:
12 : 3
Take it to the lowest form by dividing both sides by 3:
= 4 : 1
b. There were 4 students with a D grade and 8 with a B. The ratio is:
= 4 : 8
Taken to the lowest form that would be:
= 1 : 2
This means that for every student receiving a D, 2 students received an A.
c. 12 students received a C and 4 students received a D. That ratio is therefore:
= 12 : 4
Take to the lowest form by dividing both sides by 4:
= 3 : 1
