Which situation is best? a. having $3,280.00 in a savings account earning a 4.25% APR and $1,320.00 due on a credit card with a
1 answer:
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Answer:
The woman invested $15,000 at 7% interest rate and $5,000 at 6% interest rate.
Step-by-step explanation:
We are given the following in the question:
Let x be the interest earned from 7% interest rate and y be the interest earned from 6% interest rate.
The woman invested has three times as much invested at 7% as she does at 6%.
Thus, we can write the equation:
The total interest is $1,350.
Thus, we can write the equation:
Solving the two equations by substitution method:
Thus, she invested $15,000 at 7% interest rate and $5,000 at 6% interest rate.
Given:
The system of equations:
To find:
The number that can be multiplied by the second equation to eliminate the x-variable when the equations are added together.
Solution:
We have,
...(i)
...(ii)
The coefficient of x in (i) and (ii) are 1 and respectively.
To eliminate the variable x by adding the equations, we need the coefficients of x as the additive inverse of each other, i.e, a and -a So, a+(-a)=0.
It means, we have to convert into -1. It is possible if we multiply the equation (ii) by -5.
On multiplying equation (ii) by -5, we get
...(iii)
On adding (i) and (iii), we get
Here, x is eliminated.
Therefore, the number -5 can be multiplied by the second equation to eliminate the x-variable.