Of the last 20 trains to arrive at lansbury station 18 were on time considering this data how many of the next 10 trains would you expect to be on time

Which ratio is equivalent to 10: 85

△cde maps to △stu with the transformations (x, y) arrowright (x − 2, y − 2) arrowright (3x, 3y) arrowright (x, −y). if cd = a + 1, de = 2a − 1, st = 2b + 3 and tu = b + 6, find the values of a and b. the value of a is and the value of b is .

How do i do this? i don’t understand