SOLUTION: Please help with this word problem: Albert earns $78 for working 6 hours. Which equation could be used to find the number of dollars, d, that Albert earns in 9 hours? A. 78/

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Question 429283: Please help with this word problem:
Albert earns $78 for working 6 hours. Which equation could be used to find the number of dollars, d, that Albert earns in 9 hours?
A. 78/d = 9/6
B. 78d - 6+9
C. 6+9 = 78 + d
D. 6d = 78 + 9.
This is for my nephew, he is in eigth grade excelerated math and did not like my answer. He would like an explanation as to why the other answers do not work as well. He is very intelligent and has been accepted to pre-navel academy. Any help would be appreciated.
Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
Albert earns $78 for working 6 hours.
Which equation could be used to find the number of dollars, d, that Albert earns in 9 hours?
:
I don't like any of these equations; the 2nd one is not even an equation.
:
Change the 1st one to
= , that would work
6d = 9 * 78
6d = 702
d = 702/6
d = $117 earned in 9 hrs
:
:
Confirm this by finding the amt earned per hour, 78/6 = $13 per hr,
Then in 9 hrs; 9 * 13 = $117