SOLUTION: you have 250 dinners a child's plate costs $3.50 an adult's plate costs $7.00 a total of $1347.50 was collected how many plates [child and adult] were served?

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: you have 250 dinners a child's plate costs $3.50 an adult's plate costs $7.00 a total of $1347.50 was collected how many plates [child and adult] were served?      Log On


   

Question 140700: you have 250 dinners
a child's plate costs $3.50
an adult's plate costs $7.00
a total of $1347.50 was collected
how many plates [child and adult] were served?
Answer by jojo14344(1513) About Me  (Show Source):
You can put this solution on YOUR website!
Let's assigned "x"= child's plate and "y"=adult's plate.
So, x+y=250 right? (assuming all the 250plates were used)
Mark this equation 1.
Then when we multiply the child's plate "x" by $3.50) + (adult's plate "y" times $7.00)equals $1347.50. To show,
3.50%28x%29%2B%247.00%28y%29=$1347.50. Mark this equation 2.
In equation 1 we get y=250-x, then substitute this "y" value in equation 2.
Therefore,
3.50%28x%29%2B%247.00%28250-x%29=$1347.50
3.50%28x%29%2B1750.50-7.00x=1347.50
3.50x=402.50
x=115, this is # of child's plate
For adult, go back equation 1, y=250-115
y=135, # of adult's plate
In doubt? Simply check and go back equation 2,
3.50%28115%29%2B7.00%28135%29=1347.50
402.50%2B945=1347.50
$1347.50=$1347.50
Thank you,
Jojo