David helped his father stock the pond with baby catfish and blue gill. They put in a total of 75 fish. If the number of blue gill was doubled and the number of catfish tripled, there would be 175 fish in the pond. How many catfish were put in the pond?

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Answer 1 · 2016-07-07T06:40:54

25 Catfish

50 Bluegill

#x + y = 75#

#x = bluegills#
#y = catfish#

#2x + 3y = 175#

Solve for x.

#x=75-y#

Plug it back in the first equation.

#2(75-y)+3y=175#

#150-2y+3y=175#

#150+y=175#

#y=25#

25 Catfish.

Plug in #y=25# in the first equation and solve for #x#.

#x+25=75#

#x=50#

25 Catfish
50 Blue gill