Valerie is ordering salads and drinks for her friends. Salads cost $7 each, drinks cost $3 each, and there is a $5 delivery charge per order. She has $50. If she buys 3 salads, what is the maximum number of drinks she can buy?

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Answer 1 · 2017-01-21T18:24:48

Valerie can order a maximum of 8 drinks.

#S=# number of salads Valerie orders
#D=# number of drinks Valerie orders

The situation can be represented by the equation
#7S+3D+5=#Total Cost

Substituting the given information, we get
#7(3)+3D+5=50#

#color(red)(21)+3D+5=50#

#color(red)(26)+3D=50#

Subtract 26 from both sides of the equation

#26 color(red)(-26) +3D=50 color(red)(-26)#

#3D=color(red)(24)#

Divide both sides by 3

#(3D)/color(red)(3)=24/color(red)(3)#

#(cancel(3)D)/cancel(3)=8#

#D=8#

Check your answer
3 salads#xx#$7#+##color(red)(8)# drinks#xx#$3#+#$5 delivery charge
#=21+24+5#
#=50#