Can someone help me put this into an equation please?

Question

 Jack and Jill have equal amounts of money. Jack buys 7 packets of fruit gums and then has 22p left. Jill buys 3 packets of fruit gums and has £1.30 left. Make an equation and solve it to find the cost of one packet of fruit gums. Thanks

Answer 1

Since Jack and Jill have the SAME amount of money, we can use one variable to stand for that amount.  Call it m.

 

The other thing we don't know is how much a packet of fruit gum costs.  Let's call that c.

 

So the amount that Jack spend on gum has to be 7c.  Since he starts with m, the amount of money he has left after he buys the bum must be m - 7c, and that's equal to .22.  So

 

m - 7c = .22

 

So m = 7c + .22.

 

Similarly, after Jill buys 3 packets of gum, she has 1.30 left, so m - 3c = 1.30.  So

 

m = 3c + 1.30

 

Since we have two expressions for m, we know they have to be equal, so just set them equal to each other:

 

7c +  .22 = 3c + 1.30

 

That's the equation to solve.

7c +  .22 = 3c + 1.30

7c = 3x + 1.08

4c = 1.08

c = .27

 

So the cost of one packet is 27 p