SOLUTION: Two-fifths of a certain no. decreased by three-fourths is equal to seven-eights. What is the no.?

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Question 12055: Two-fifths of a certain no. decreased by three-fourths is equal to seven-eights. What is the no.?




Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Let n be the number you are looking for.
From the description, you can write:
%282%2F5%29n+-+%283%2F4%29+=+7%2F8 Let's clear the fractions by multiplying through by the common denominator of 40.
40%282%2F5%29n+-+40%283%2F4%29+=+40%287%2F8%29
16n+-+30+=+35 Add 30 to both sides.
16n+=+65 Divide both sides by 16.
n+=+65%2F16 = 4 1/16
The number is: 4 1/16 That's 4 and 1/16
Check:
%282%2F5%29%2865%2F16%29+-+%283%2F4%29+=+13%2F8+-+6%2F8 = 7/8