Pretty sure you’ll save 1 dollar for b and and lose one dollar for a
Average speed of cyclist = x
average speed of car = 3x
x = 225/5
x = 45km/h
3x = 3(45)
3x = 135km/h
average speed of cyclist = 45km/h
average speed of car = 135km/h
247 divided by 10^2 is 2.47 and 247 times 10^2 is 24,700
The 11th triangular number = 66