Evaluate f(x)=4x+5 when x=4.

21

Step-by-step explanation:

=4x+5

=4*4+5

=16+5

=21

the amount invested at 13% is $9748

the amount invested at 5% is $3420

Step-by-step explanation:

Let x represent the amount invested at 13%.

Let y represent the amount invested at 5%.

$13,168 is invested, part at 13 % and the rest at 5%. This means that

x + y = 13168

The formula for determining simple interest is expressed as

I = PRT/100

Where

I represents interest paid on the loan.

P represents the principal or amount taken as loan

R represents interest rate

T represents the duration of the loan in years.

Considering the amount invested at 13%,

P = x

R = 13%

T =1 year

I = (x × 13 × 1)/100 = 0.13x

Considering the amount invested at 5%,

P = y

R = 5%

T = 1 year

I = (x × 5 × 1)/100 = 0.05y

If the interest earned from the amount invested at

13% exceeds the interest earned from the amount invested at

5% by $1438.24, it means that

0.13x - 0.05y = 1438.24 - - -- - - - - -1

Substituting x = 13168 - y into equation 1, it becomes

0.13(13168 - y) - 0.05y = 1438.24

1711.84 - 0.13y - 0.05y = 1438.24

- 0.13y - 0.05y = 1438.24 - 1711.84

- 0.08y = - 273.6

y = - 273.6/- 0.08

y = 3420

x = 13168 - y = 13168 - 3420

x = 9748