15 rulers cost £3 how much do 40 rulers cost?

The cost of the 40 rulers is £8 .

Step-by-step explanation:

As given in the question

15 rulers cost £3

i.e

15 rulers = £3

Cost of the one ruler.

1 ruler cost =  £ 0.2

Now find out the cost for 40 rulers .

Cost for 40 rulers = 40 × 0.2

                              = £8

Therefore the cost of the 40 rulers is £8 .

x= -3 and

step-by-step explanation:

to find the roots of a cubic, use division or factoring to find the factors then set equal to 0. as this is a difference of cubes, it factors into

where a is the cube root of .

here   this is 27 and the cube root of 27 is 3. so we write using the form:

.

set each factor to 0 and solve for x.

x-3=0

x=3

the quadratic expression does not factor and must be solved using the quadratic formula.

where a = 1, b=3, and c=9

this cubic has two complex roots.