There are 33 of them altogether and pay £311 in total. How many kids are in the family? Adults pay £15 and kids pay £7

Step-by-step explanation

We can then write this two equations :

          x+y= 33

          15x+7y= 311

to do that we should combine them both in a way that help us get rid of one of the variables.

             Let's multiply the first equation by -7 to get rid of y by adding it to thr second equation

             -7x-7y= -231

        now add both equations .

              15x+7y-7x-7y=311-231

    we get :  8x = 80

as you notice y is gone and we get a classic easy equation to solve

                x= 80/8

                   = 10

so the number of adults is 10

let's go back to the first equation ( x+y= 33) and replace x with 10

                10+y= 33

                  y= 33-10

                     =23

let's check using the second equation :

            (10*15)+(23*7) = 311

that is true

so :

4a. is 3 miles every hour

4b. is 1/3 of an hour per mile

step-by-step explanation:

i got 10.28 but that rounds up to 10.3