SOLUTION: At work one day, Erica received 28 packages. Speedy delivery delivered twice as many as Ralph's Express, while Ralphs Express delivered four more than Send Quick Package service.

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Question 179876: At work one day, Erica received 28 packages. Speedy delivery delivered twice as many as Ralph's Express, while Ralphs Express delivered four more than Send Quick Package service. How many packages did each service deliver to Erica.
Speedy Delivery
Ralph's Express
Sendquick
Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
At work one day, Erica received 28 packages. Speedy delivery delivered twice as many as Ralph's Express, while Ralphs Express delivered four more than Send Quick Package service. How many packages did each service deliver to Erica.
Speedy Delivery
Ralph's Express
Sendquick
let number of packages speedy,ralphs,and sendquik delivered be a,b,and c respectively
:
a=2b.......eq 1
b=c+4......eq 2
a+b+c=28....eq 3
:
rewrite eq 2 to c=b-4 and take that value and the value of a in eq 1 and plug them into eq 3
:
(2b)+b+(b-4)=28
:
4b=32
:
highlight%28b=8%29packages delivered by ralphs
:
highlight%28a=2b=2%288%29=16%29packages delivered by speedy
:
highlight%28c=b-4=8-4=4%29package delivered by sendquick