Calculate how much is a pint of beer and a packet of crisp? 3 Pints of beer and 2 packets of crisp = £8.60 4 Pints of beer and a packet of crisp =£10.20

Question

Calculate how much is a pint of beer and a packet of crisp?

3 Pints of beer and 2 packets of crisp = £8.60
4 Pints of beer and a packet of crisp =£10.20

Answer 1

let b=# of beers

let c=# of crisps

3b+2c=8.60

4b+c=10.20

multiply second equation by 2

8b+2c=20.40

subtract first equation from new second equation

8b+2c=20.40

-

3b+2c=8.60

5b=11.80

b=11.80/5

b=2.36 pounds

using second original equation, substitute b=2.36

4(2.36)+c=10.20

9.44+c=10.20

c=10.20-9.44

c=0.76  pounds

check:3(2.36)+2(0.76)=7.08+1.52=8.60

 

Answer 2

Choose a variable to unknowns, What problem is asking to find out:

   

    B - pint of beer

    P- packet of crisp

 

    Then convert statements of the problem into algebraic expression:

 

      3B + 2P = 8.60

      $B + 1P = 10.20

 

     Solve this System of equation