Question about currency exchange

if 55lrd=1usd and 100lrd=1chd
how much does ? chd=1usd?

Tickets to a science exposition cost $5.75 each for studentd and $7.00 for adults.how many students and adults went if the ticket charge was $42.75

Players on the school soccer team are selling candles to raise money for an upcoming trip. each player has 24 candles to sell. if a player sells 4 candles a profit of$30 is made. if he sells 12 candles a profit of $70 is made. determine an equation to model his situation?

Solve the equation: x - 9 = -6 + 5 a. 21 b. 7 c. 14 d. 2