Word Problems into Systems of Equations. Help Please!?

I need help on turning the word problems into Systems of Equations. Can somebody help me out? I wrote each problem exactly how they are in the book.


Here are the word problems:





1. The rate of growth of participation (age 6 and older) in sports featured in the X-Games is surpassing that for older sports such as football and baseball. The most popular X-Game sport is inline roller skating, followed be skateboarding. In 2000, the total number of participants in both sports was 40.6 million. if the number of participants in roller skating was 5.8 million more than twice the number of participants in skateboarding, find the number of participants in each sport.





2. Terry Watkins can row about 10.6 kilometers in 1 hour down stream and 6.8 kilometers up stream in 1 hour. Find how fast he can row in still water, and find the speed of the current.





3. Find how many quarts of 4% butterfat milk and 1% butterfat milk should be mixed to yield 60 quarts of 2% butterfat milk.

Word Problems into Systems of Equations. Help Please!?
What a long and irrelevant setup on #1. Anyway, the transition from words to equations begins with defining variables.





Let x = # of roller skaters


Let y = # of skateboarders.





From the sentence "In 2000, the total number...", we know that (x+y) = 40,600,000. From the next sentence, we know that x = 5,800,000 + 2y. So the system is:





x + y = 40,600,000


x = 2y + 5,800,000





#2)





Let x = his rowing speed in km/hr


Let y = the river current speed in km/hr





10.6 = x + y [the speeds are in the same direction]


6.8 = x - y [the speeds are in opposite directions]





#3)





Let x = # of quarts of 4%


Let y = # of quarts of 1%





0.04x + 0.01y = 0.02*60 [the final milk must be 2%]


x + y = 60
Reply:x= # in skateboarding


2x+5.8 = roller skating


x+2x+5.8 = 40.6


3x=34.8


x=11.6 million in skateboarding


29 million in roller skating





x= speed in still water


10.6-x is speed of current


x-(10.6-x)=6.8


2x-10.6=6.8


2x=17.4


x=8.7 kph is his speed


1.9 kph is the speed of stream





x= amt of 4% milk


60-x=amt of 1%


.04x+.01(60-x)=.02(60)


.04x+.6-.01x=1.2


.03x=.6


x=20 qts of 4%


40 qts of 1%



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