Algebra word problem.

Question

Sam invested 26,000. Some was invested in bonds that made 5% profit, and the rest put into stocks that made 8% profit. How much did Sam invest in bonds if his total profit on both types of investments was $1,420?

Answer 1

This gives us a system of equations to solve.  Let set x = money invested at 5% and y = money invested at 8%.

 

Therefore:

 

x + y = 26000.

 

To calculate interest on an investment for 1 year, simply multiply the percent (as a decimal) by the amount invested.  Therefore:

 

0.05x + 0.08y = 1420.

 

Solving the first equation for y (y = 26000 - x) allows us to substitute into the second equation and solve.

 

0.05x + 0.08(26000 - x) = 1420

0.05x + 2080 - 0.08x = 1420

-0.03x + 2080 = 1420

-0.03x = -660

x = 22000

 

Since x and y add to 26000, y = 4000.

 

Sam invested $22,000 at 5% and $4000 at 8%.