Larry Mitchell invested part of his $11,000 advance at 3% annual simple interest in the rest at 4% annual simple interest

Question

if his total yearly interest from both accounts was $420, find the amount invested at each rate.

The amount invested at 3% is $....

The amount invested at 4% is $....

Answer 1

X+y = 11000

0.03X + 0.04Y = 420

0.03X + 0.04(11000-x) = 420

0.03x + 440 - 0.04x = 420

-0.01x + 440 = 420

-0.01x = -20

x = 2000

The alleged answer is

$2000 at 3% and 9000 at 4%,

which shall return 0.03 * 2000 + 0.04*9000

= 60 + 360

= 420

The OFFICIAL answer is $2000 at 3% and 9000 at 4%