John buys 3 packets of washing powder A. and 5 packets of washing

powder B. and spends #4 900. john has 3 packets of washing powder

B that is not needed and returns these to the shop and gets a full

refund. He also buys 6 further packets of washing powder john pays an #1740 in addition to the money received as refund.

How much does a packer of each washing powder cost:

A costs 600.

B costs 620

A costs #711.5385

B costs #553.0769

Step-by-step explanation:

Let cost of powder A be x and powder B be y

When he's given refund, equation can be written as

6x=1740+3y

6x-3y=1740 eqn 1

2x-y=870 making y the subject of the formula

Y=2x-870

Also, from the initial shopping

3x+5y=4900 eqn 2

Substituting the formula of y into eqn 2 we obtain

3x+5 (2x-870) = 4900

3x+10x-4350=4900

13x=4900+4350=9250

X=9250/13 = 711.5385

Y=2x-870=2 (711.5385) - 870 = 553.0769