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
$=21+24+5$
$=50$