if in 1 second the jet goes 428 meters and you want to know how long it takes to go 237 meters you just divide 237/428
it can be written like this
_1_ = __x__
428 237
cross multiply
428 times x = 1 times 237
428x=237
divide by 428 on both sides
x= 237/428
x=0.5537 seconds
