Algebra

[lem0n84]

Question:
Sue breeds two types of dogs: Labs and Bulldogs.
Bulldogs bring in twice as much profit as Labs.
Sue sells 20 dogs altogether for a total profit of $150.
If P is the profit when Sue sells one Lab, find the expression for how many of each dog she sold in terms of P.

My working so far:

L = Labs
B = Bulldogs.

L + B = 20
PL + 2PB = 150

I tried to solve it simultaneously:
PL + 2PB = 150P
PL + PB = 20P

and got ->PB = 130P

But answer says B = 150/P - 20
and L = 40 - 150/p

Where did I go wrong?
Cheers

 

[topsquark]

L + B = 20
PL + 2PB = 150

I tried to solve it simultaneously:
PL + 2PB = 150P
PL + PB = 20P

You suddenly sprouted a new P on the RHS of the PL + 2PB = 150 equation...

-Dan

 

[Steven G]

For the record, when you have PB = 130P you should then get P(B-130)=0 so either P=0 or B=130. Since there is a profit made, then P is not 0, so B=130.