A train is moving at a uniform speed of 80 kilometre per hour. a) how far will it travel in 15 minutes
b) find the time required to cover a distance of 250 km. { as per direct and inverse propositions}.

A train is moving at a uniform speed of 80 kilometre per hour.

a) how far will it travel in 15 minutes

b) find the time required to cover a distance of 250 km. { as per direct and inverse propositions}.

a)

Given that the train is moving at a uniform speed of 80 km/h.

Time taken = 15 minutes

First we will convert the time

Now we will calculate the distance

We know,

Substituting the values in the given formula

Distance covered in 15 minutes = 20 km

b)

Given that the train is moving at a uniform speed of 80 km/h.

Distance covered = 250 km

Calculating the time

We know,

Substituting the values in the given formula

The answer is in the image 

The total nom of  code that can be used is equal to 5+3 = 8

Salesperson will make 6% of 1800

=(6/100)*1800

=108

Salesperson will make $108 in $1800 sales

The wood before starting =12 feet

Left wood=6 feet

Wood used till now=12-6=6 feet

Picture frame built till now= 6/(3/4)

=8 pieces

Therefore, till now 8 pieces have been made.

The wood before starting =12 feet

Left wood=6 feet

Wood used till now=12-6=6 feet

Picture frame built till now= 6/(3/4)

=8 pieces

Therefore, till now 8 pieces have been made.

Salesperson will make 6% of 1800

=(6/100)*1800

=108

Salesperson will make $108 in $1800 sales

30% of 420 are first year students

first year students = (30/100 )*420

=126 students

Student who are not in first year = 420-126

=294 students  

Let the father's age be x and son's be y

10 years before-

Father age=x-10

sons age=y-10

Given,

x-10=10(y-10)

x-10=10y-100

Given present age of father=40

therefore,

x=40

40-10=10y-100

10y-100=30

10y=130

y=130/10

y=13

Therefore present age of son=13years

Cost of 6 gallons =$15

Cost of 1 gallon =15/6

                           =$2.5

Cost of 7 gallons=$2.5 * 7

                           =$17.5