If the simple interest on $900 for 3 years was 108, what was the rate of interest?

Simple interest can be found using the simple interest formula:

I = interest

P = principal

r = interest rate

t = time

I = P × r × t.

In our instance,

I = $108

P = $900

r = ?

t = 3.

Plug our numbers into the simple interest formula above.

$108 = ($900) × r × (3).

Simplify the right side

$108 = $2,700r.

Divide each side by $2,700.

0.04 = r.

0.04 × 100 = 4%

The rate of interest is 0.04 or 4%

y=mx+b

step-by-step explanation:

m slope

b y-intercept

(0,-3) see attached graph

step-by-step explanation:

a. to solve the system, graph the two equations.

x = y+3 becomes y=x-3 has m=1/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move up 1 unit and 1 unit to the right. plot a point and connect.

y=-4x+3 has m =-4/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move down four units and to the right 1 unit. plot a point and connect.

the solution is the point (x,y) where the two lines intersect. by the graph below it is (0,-3).

b. to solve by substitution, substitute y = -4x-3 into x= y+3

x= (-4x-3) +3

x=-4x

5x=0

x=0

now substitute x = 0 back in to find y.

y= -4(0)-3

y=0-3

y=-3

solution is (0,-3)

c. use elimination by adding the equations together.

x-y=3

4x+y=-3

5x=0

x=0

then substitute into one equation to find y.

y=-4(0)-3

y=-3