Respuesta :
take both equations and write a new one incorporating both.
Solve the new equation for p.
Use your p solution to plug back into an original equation and solve for w.
Check your solutions by checking them in both original equations.
Solve the new equation for p.
Use your p solution to plug back into an original equation and solve for w.
Check your solutions by checking them in both original equations.
p= # of popcorn
w= # of waters
QUANTITY EQUATION
p + w= 108
COST EQUATION
$1.25p + $0.75w= $105
STEP 1:
solve for one variable in cost equation
p + w= 108
subtract w from both sides
p= 108 - w
STEP 2:
substitute p=108-w in for p in cost equation
$1.25p + $0.75w= $105
1.25(108-w) + 0.75w= 105
multiply 1.25 by all in parentheses
(1.25*108)+(1.25*-w)+0.75w= 105
135 - 1.25w + 0.75w= 105
combine like terms
135 - 0.5w= 105
subtract 135 from both sides
-0.5w= -30
divide both sides by -0.5
w= 60 water bottles
STEP 3:
substitute w=60 in either equation to find p
1.25p + $0.75w= $105
1.25p + 0.75(60)= 105
1.25p + 45= 105
subtract 45 from both sides
1.25p= 60
divide both sides by 1.25
p= 48 popcorn
CHECK:
p + w= 108
60 + 48= 108
108= 108
ANSWER: There were 60 popcorn sold and 48 waters sold.
Hope this helps! :)
w= # of waters
QUANTITY EQUATION
p + w= 108
COST EQUATION
$1.25p + $0.75w= $105
STEP 1:
solve for one variable in cost equation
p + w= 108
subtract w from both sides
p= 108 - w
STEP 2:
substitute p=108-w in for p in cost equation
$1.25p + $0.75w= $105
1.25(108-w) + 0.75w= 105
multiply 1.25 by all in parentheses
(1.25*108)+(1.25*-w)+0.75w= 105
135 - 1.25w + 0.75w= 105
combine like terms
135 - 0.5w= 105
subtract 135 from both sides
-0.5w= -30
divide both sides by -0.5
w= 60 water bottles
STEP 3:
substitute w=60 in either equation to find p
1.25p + $0.75w= $105
1.25p + 0.75(60)= 105
1.25p + 45= 105
subtract 45 from both sides
1.25p= 60
divide both sides by 1.25
p= 48 popcorn
CHECK:
p + w= 108
60 + 48= 108
108= 108
ANSWER: There were 60 popcorn sold and 48 waters sold.
Hope this helps! :)