SOLUTION: What is the model for unkowns for this problem: Mrs. B invested $30,000: part at 5%, and part at 8%. The total interest on the investment was $2100. How much did she invest at each

Question 559161: What is the model for unkowns for this problem: Mrs. B invested $30,000: part at 5%, and part at 8%. The total interest on the investment was $2100. How much did she invest at each rate?

I started here: $30,000-x=7
x=.05
y=.08
Stuck now...
Answer by scott8148(6628) (Show Source): You can put this solution on YOUR website!
x + y = 30000 ___ x = 30000 - y

(5%)x + (8%)y = 2100

substituting ___ (.05)(30000 - y) + (.08y) = 2100 ___ 1500 + .03y = 2100

solve for y; then substitute back to find x
RELATED QUESTIONS
What is the mathematical expression of this. The total interest earned after one year... (answered by Alan3354,ikleyn)

Mr B invested p30000:part at 5% and part at 8%.The total interest on the investment was... (answered by ikleyn,greenestamps)

the total interest earned after one year Php 100 000 is invested, part of 6% annual... (answered by greenestamps)

Please hep me solve this word problem. A total of $8000 dollars is invested for one year, (answered by solver91311)

I need help with this problem please: Lane invested $14,000, part at 15% and part at... (answered by checkley75)

Larry Mitchell invested part of his $30,000 advance at 5% annual simple interest and the... (answered by greenestamps)

the total interest earned after one year Php 100 000 is invested, part of 6% annual... (answered by ikleyn)

Stan invested $5,000, part at 8% and part at 17%. If the total interest at the end of the (answered by stanbon)

Bob invested $24000. He invested part of it at 8% interest per year and the rest at 10%... (answered by richwmiller,greenestamps)