Answer :
x= sandwiches
y= bottles of water
QUANTITY EQUATION
x+y= 200
COST EQUATION
$3x + $0.75y= $318.75
STEP 1
solve for one variable in quantity equation and substitute in cost equation
x+y= 200
subtract y from both sides
x= 200-y
STEP 2
substitute 200-y in for x
$3x + $0.75y= $318.75
3(200-y) + 0.75y= 318.75
600 - 3y + 0.75y= 318.75
combine like terms
600 - 2.25y= 318.75
-2.25y= -281.25
divide both sides by -2.25
y= 125 number of water bottles
STEP 3
substitute y=125 in either equation
x+y= 200
x + 125= 200
x= 75 sandwiches
ANSWER: There were 75 sandwiches and 125 bottles of water.
Hope this helps! :)
y= bottles of water
QUANTITY EQUATION
x+y= 200
COST EQUATION
$3x + $0.75y= $318.75
STEP 1
solve for one variable in quantity equation and substitute in cost equation
x+y= 200
subtract y from both sides
x= 200-y
STEP 2
substitute 200-y in for x
$3x + $0.75y= $318.75
3(200-y) + 0.75y= 318.75
600 - 3y + 0.75y= 318.75
combine like terms
600 - 2.25y= 318.75
-2.25y= -281.25
divide both sides by -2.25
y= 125 number of water bottles
STEP 3
substitute y=125 in either equation
x+y= 200
x + 125= 200
x= 75 sandwiches
ANSWER: There were 75 sandwiches and 125 bottles of water.
Hope this helps! :)