Question

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

Answer 1

Explanation

1. Let x be the number of adults and y the number of kids

We can then write this two equations :

x+y= 33

15x+7y= 311

• let's solve the two eaquations

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 :

• the number of adults is 10
• the number of kids is 23