A cellphone store has 120 cell phones in stock. Of these, 45 have keyboards. The manager of the store wants to add more cell phones with keyboards so that 40% of the stock has keyboards.

5

Step-by-step explanation:

Let x be the number of cell phones with keyboards needed.

40% =

=

x+45 = 40 -----1

x+120 = 100 -----2

You would want to make the total of 1 the same as 2.

1×: 2.5+112.5 = 100 -----3

Now 2 and 3 are equal.

x+120 = 2.5x+112.5

Isolate the x and numbers.

120-112.5 = 2.5x-x

Simplify.

1.5x = 7.5

x = × 7.5

x = 5

The manager of the store needs to add 5 more cell phones with keyboards.

step-by-step explanation:

there is a formula i can give you:

it is r^2*n*sin(360/n) divided by 2 where r represents the "radius" and n is the number of sides.

plug them in:

(10sqrt(3))^2*6*sin(360/6) divided by 2

100*3*6*sin(60) divided by 2

900*sin(60)

900*sqrt(3)/2

450*sqrt(3)

approx is 779.4 cm^2

i believe it is 0.1m because the measurement of 30.4m limits how precise you can be

you can only be as precise as the least precise measurement