The American swallow can lift into the air and carry a maximum of 5 pounds of weight, while the European swallow can lift and carry twice the weight as the American swallow.  If there was a flock of 90 swallows, containing twice as many American as European swallows, what is the maximum combined weight the flock can carry?
How many American swallows are there? ** If "x" is the number of European swallows, then, for every one European swallow, there would be 2x American swallows.
Write an equation ** Thus, the total number of swallows would be 2x+x=90 swallows
How many European swallows are there? ** Thus, the number of European swallows x=<<30=30>>30.
How many American swallows are there? ** And the number of American swallows is 90-30=<<90-30=60>>60.
How much can a European swallow carry? ** A European swallow can carry twice what an American swallow can carry, or 2*5=<<2*5=10>>10 pounds.
How much can 30 European swallows carry? ** 30 European swallows can carry a maximum of 30*10=<<30*10=300>>300 pounds.
How much can 60 American swallows carry? ** 60 American swallows can carry a maximum of 60*5=<<60*5=300>>300 pounds.
What is the maximum combined weight the flock can carry? ** Thus, a flock of 90 birds, with 30 European and 60 American swallows, can carry 300+300=600 pounds
#### 600