Luke invested some money at 7%interest and the same amount at 10%. His total interest for the year was $150 les than one-tenth of the total amount he invested . how much did he invest at each rate?

Question

mathstudent55 · Answer

0.07x + 0.1x = 0.1(2x) - 150

dtan5457 · Answer

@mathstudent55 

how did you get 2x?

mathstudent55 · Answer

Notice the wording of the problem and the way I chose the variable.

dtan5457 · Answer

2x because there is 2 interest, so two total values right?

mathstudent55 · Answer

Luke invested some money at 7% interest and the same amount at 10% interest.
He invested x at 7% and x at 10%
I chose x to represent the investment at each interest. We are told the two amounts are equal. That is why we can use the same variable x t represent the two parts of his investment.

mathstudent55 · Answer

"His total interest for the year was $150 less than one-tenth of the total amount he invested."
Here we are dealing with the total investment. If each part of the investment is x, then the total investment is 2x.

dtan5457 · Answer

Oh, got it. Thanks

mathstudent55 · Answer

You're welcome.

anonymous · Answer

thank you sooo much mathsutudent55, great help

mathstudent55 · Answer

You are welcome.