MATHS(F 1) Q.1

a butcher sells beef at $20 per catty.a supermarket sells beef of the same quality at $16.50 per pound.given that 3 catties equal 4 pounds,which one sells beef at a lower price.
From the question, we know that
buy 3 catties beef equal buy4 pounds beef
For a a butcher sells beef at $20 per catty
If I buy 3 catties, I pay $20 *3= $60
For a supermarket sells beef of the same quality at $16.50 per pound
If I buy 4 pounds, I pay $16.50*4=66
Now, I get the same quantity beef from butcher and supermarket
Since the money I pay for supermarket is larger than butcher
So butcher sells beef at a lower price.