Lamar invested his savings in two investment funds. The amount he invested in Fund A was 4 times as much as the amount he invested in Fund B. Fund A returned a 3% profit and Fund B returned a 6% profit. How much did he invest in Fund B, if the total profit from the two funds together was $1620?

Question

anonymous · Answer

If we use 
$$ A = \ \textrm{amount invested in Fund A}$$
$$ B = \ \textrm{amount invested in Fund B}$$
$$P_A = \textrm{Profit on Fund A}$$
$$P_B = \textrm{Profit on Fund B}$$

How are each of those variables related?

anonymous · Answer

In the problem it says that the amount invested in Fund A was 4 times the amount invested in Fun B, so we can say

$$ A = 4B$$

The problem also says that the Profit on Fund A was 3%.  3% = 3/100 so we can say

$$P_A = \frac{3}{100}A$$

Profit on Fun B was 6%.

$$P_B = \frac{6}{100}B$$

And lastly, that total Profits were $1620

$$P_A + P_B = $1620$$

How are P_A and P_B related to A and B?  And how is A related to B?