Question #157eb

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Answer 1 · 2018-02-03T04:40:40

Betsy sold 60 and daisy sold 30

Assuming Betsy sells #b# gallons of milk and Daisy sells #d# gallons of milk:

# b + d = 90 # because 90 gallons were sold totally

Therefore #b = 90 - d# (Equation 1)

Betsy earns $#4b# because her milk costs $4 a gallon

Daisy earns $#8d# because her milk costs $8 a gallon

Therefore #4b + 8d = 480# (Equation 2)

Now we must use simultaneous equations to arrive find the values of #b# and #d#

Substituting equation 1 into 2,

We get 4(90 - d) + 8d = 480
By solving we get 4d = 480 - 360
Therefore d = #120/4# = 30

Therefore from equation 1,
b = 90 - 30 = 60

Therefore Betsy sold 60 gallons and daisy sold 30.