SOLUTION: Cleaning sidewalks. Edgar can blow the leaves off the sidewalks around the capitol building in 2 hours using a gasoline-powered blower. Ellen can do the same job in 8 hour

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Question 203389This question is from textbook
: Cleaning sidewalks. Edgar can blow the leaves off the
sidewalks around the capitol building in 2 hours using a
gasoline-powered blower. Ellen can do the same job in
8 hours using a broom. How long would it take them
working together?

Running backs. In the playoff game the ball was carried
by either Anderson or Brown on 21 plays. Anderson gained
36 yards, and Brown gained 54 yards. If Brown averaged
twice as many yards per carry as Anderson, then on how
many plays did Anderson carry the ball?

I am really bad at word problems i just never know how to lay them out into an equation.
I appreciate all your help!
This question is from textbook

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Cleaning sidewalks. Edgar can blow the leaves off the
sidewalks around the capitol building in 2 hours using a
gasoline-powered blower. Ellen can do the same job in
8 hours using a broom. How long would it take them
working together?
:
A typical shared work problem, learn this method and you can handle most of them
Let t = time required, working together
Let the completed job = 1
t%2F2 + t%2F8 = 1
Multiply by 8 and you have
4t + t = 8
5t = 8
t = 8%2F5
t = 1.6 hrs
;
Check: 1.6%2F2 + 1.6%2F8 = 1
:
:
Running backs. In the playoff game the ball was carried
by either Anderson or Brown on 21 plays. Anderson gained
36 yards, and Brown gained 54 yards. If Brown averaged
twice as many yards per carry as Anderson, then on how
many plays did Anderson carry the ball?
:
let a = no. of plays by Anderson
let b = no. of plays by Brown
:
total no. of plays:
a + b = 21
b = (21-a); use this form for substitution
:
B's av carry = twice A's average carry
54%2Fb = 2(36%2Fa%29)
54%2Fb = 72%2Fa%29
Cross multiply
54a = 72b
Substitute (21-a) for b
54a = 72(21-a)
54a = 1512 - 72a
54a + 72a = 1512
126a = 1512
a = 1512%2F126
a = 12 carries for Anderson
:
You should check this solution by finding b and substitution in equation