Question

If clay cost $16.50 for 50lb how much does clay cost for 45 pounds

Answer 1

45 divided by 50= 90%
0.9*16.50=14.85

Answer 2

Ratio and propoertion or logic

ratio
cost:amount=16.5/50
16.5/50=x/45
times both sides by 50*45
16.5*45=50x
742.5=50x
divide both sides by 50
14.85=x
the answer is $14.85 for 45lb

or, math
16.5 for 50
1.65 for 5
50-5=45
16.5-1.65=14.85

answer is $14.85 for 45lb