Nico is saving money for his college education. He invests some money at 8​%, and ​$1800 less than that amount at 5 %. The investments produced a total of ​$261 interest in 1 yr. How much did he invest at each​ rate?

amount at 8% --- x

amount at 5% ---- x-1800

.08x + .05(x-1800) = 261
each term times 100
8x + 5(x-1800) = 26100

solve for x