There are an average of 34 bears and dogs. The bears eat 1/2 can of food and the dogs eat 1 1/2 can of food per day. In all, they eat about 36 cans a day. How many bears and dogs do the shelter have?
how did u get ur answer? i dont know how to do it:( THANKS
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Let's make x the number of bears and y the number of dogs.
# of bears + # of dogs= 34
x + y = 34
amount bear eats + amount dogs eat = 36
.5x + 1.5y = 36
Your two equations right now are:
x + y = 34
.5x + 1.5y = 36
Find x by getting it on one side
x = 34 - y
Sub in for x in the second equation
.5(34-y) + 1.5y = 36
17 - 0.5y + 1.5y = 36
Solve for y
1y = 19
Therefore, there are 19 dogs. Now sub in the number of dogs into one of the equations.
x + 19 = 34
x = 15
You have 2 unknowns (how many bears and how many dogs) so you need 2 equations.
You know that there are 34 bears and dogs so your first equation is:
B+D=34
**I am not sure on the wording of average. If it means an average of 34 bears and 34 dogs your equation would be:
(B+D)/2 = 34
However, I think what the problem means is what I have originally for the first equation.
You also know that a dog eats 1.5 cans of food and a bear eats .5 cans for a total of 36 cans so your second equation is:
.5B + 1.5D = 36
Now that you have your two equations:
B+D=34
.5B + 1.5D = 36
Solve one to find B in terms of D:
B = 34 - D
Now, replace B in the second equation with what you just found:
.5(34 - D) + 1.5D = 36
Now solve for D:
D=19
Take this value and plug back into either equation to find B.
Does that make sense?
I think it is 36*.75=27 Dogs (.5 Bear), (.5 Dog) (.5 Dog) (.5 Dog)= 2 can food
36*.25=9 Bears
B = bears, D = dogs
B+D = 34 (in total of bears and dogs, there are 34 of them)
.5B + 1.5D = 36 (bear's food plus dog's food per day is 36)
B+D = 34
.5B + 1.5D = 36
multiply second equation by -2
B+D = 34
-B -3D = -72 Cancel out B's
__________
-2D = -38
D = 19
Plug D back to first equation
B + 19 = 34
B = 15
15 Bears and 19 Dogs
Let the no of dogs be X
No of bears = 34 - X
No of cans eaten per day = 1.5X + 0.5 ( 34 - X) = 36
1.5X + 17 - 0.5X = 36
X = 19
ANSWER 19 dogs and 15 bears
CHECK
19 X 1.5 = 28.5
15X 0.5 = 7.5
Total = 36 cans
1/2b+3/2d=36
1/2b+3/2(34-b)=36
multiply the whole equation by 2 then...
b+3(34-b)=72
simplify!
b+102-3b=72
simplify more
-2b+102=72
-102 -102
-2b=-30
divide by -2 on both sides
b=15
so there are 15 bears and 19 dogs