$8,000 is invested in two different accounts earning 3% and 4% interest. If the two accounts earn a total of$295 in interest, how much money was invested at 3%?

The money invested at 3% is $$2500$. Explanation: We call the quantity invested at 3% as $X$and the quantity invested at 4% as $Y$. Than we have that $$X+Y=8000$$ and also $$X\times 3/100+Y\times4/100=295.$$ We are interested in $X$so from the first equation we have $Y = 8000 - X$and we substitute in the second equation $$X\times 3/100+(8000-X)\times4/100=295$$ and we solve for $X\$
$$3X-4X+32000=29500$$
$$-X=29500-32000$$
$$X=2500.$$