SOLUTION: The time T necessary to make an enlargement of a photo negative varies directly as the area A of the englargement. If 30 seconds are required to make a 3-by-5 englargement, find th

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Question 127061: The time T necessary to make an enlargement of a photo negative varies directly as the area A of the englargement. If 30 seconds are required to make a 3-by-5 englargement, find the time required for a 5-by-7 englargement
Answer by edjones(7311) About Me  (Show Source):
You can put this solution on YOUR website!
3*5=15
5*7=35
Proportion:
Let x be time required to develop a 5-by-7.
x/30=35/15
30x/30=30*35/15
x=70 sec.
.
Ed