Answer:
$3
Step-by-step explanation:
Given data
Let the cost of drinks be x
and the cost of hotdogs be y
so
3x+4y=15-------1
also
3x+y= 10.5------2
solve 1 and 2
3x+4y=15
-3x+y= 10.5
3y= 4.5
divide both sides by 3
y= 4.5/3
y= $1.5
Put y= 1.5 in 1
3x+4(1.5)=15
3x+6= 15
3x=15-6
3x= 9
x= 9/3
x= $3
Hence the cost of a drink is $3
