A woman buys "x" cakes at 45p each and (x+8) cakes at 55p each. \If she wishes to have change from a £20 note work out what "x" is?

I have come up with :

0.45x+0.55(x+8)=<20

Am I on the right track?

And...

A boy buys some packets of sweets for £1.20. If the sweets had been 3p a pack cheaper he would have recieved 2 more packets for his money. How many packets did he buy?

I got 78 for my answer, is this correct?

Thanks in advance :)

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