U=X^0.5Y^0.5

I=100 X=$19 Y=$18 price of X=$23 (higher than before)

1. find income and substitution effect from price getting higher than before for two utility functions
2. if in competitive equilibrium, find optimal consumption bundle as price ratio function for total endowment
3. find competitive equilibrium starting from endowment point, find equilibrium consumptions, price ratios, and consumers' utility levels.