SOLUTION: Loyola Heights has 3000 phones of which 3/5 are dial phones. If 2/3 of these dial phones are replaced by digital phones and 400 additional digital phones are installed, what fracti

Algebra ->  Numeric Fractions Calculators, Lesson and Practice -> SOLUTION: Loyola Heights has 3000 phones of which 3/5 are dial phones. If 2/3 of these dial phones are replaced by digital phones and 400 additional digital phones are installed, what fracti      Log On


   

Question 854207: Loyola Heights has 3000 phones of which 3/5 are dial phones. If 2/3 of these dial phones are replaced by digital phones and 400 additional digital phones are installed, what fraction of the phones are digital now?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = number of dial phones
Let +b+ = number of digital phones
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+a+=+%283%2F5%29%2A3000+
+a+=+9000%2F5+
+a+=+1800+
and
+b+=+%282%2F3%29%2A1800+
+b+=+1200+
But now +a+ is +1200+ less, so
+a+=+600+
400 additional digital phones are installed, so
+b+=+1200+%2B+400+
+b+=+1600+
Find +b+%2F+%28+a+%2B+b+%29+
+b+%2F+%28+a+%2B+b+%29+=+1600+%2F+%28+600+%2B+1600+%29+
+b+%2F+%28+a+%2B+b+%29+=+1600+%2F+2200+
+b+%2F+%28+a+%2B+b+%29+=+8%2F11+
8/11 of the phones are digital