nico is saving money for his college education. He invests some money at 6%, and $1400 less that that amount at 5%. The investments produced a total of $172 interest in 1 yr. how much did he invest at each rate?

Answer 1

Let x be the amount he invested at 6%.
Then x-1400 is the amount he invested at 5%.

Total interest after 1 year
x*0.06+(x-1400)*0.05=172
0.11x=172+1400*0.05
0.11x=242
x=2200

Check
2200*0.06+800*0.05=132+40=172 ok.