A train covers the distance between two cities A and B at 70km/h during certain time. If it goes 10km/h faster, it will cover the same distance in one hour less. Find the distance between the two cities and the time it takes to do the first trip

distance between 2 cities is 490km

time taken for first trip is 7 hours

Step-by-step explanation:

speed. time

70 x

10. 1

= 10x =70*1

x=70/10

=7 hours

distance= speed*time

=70*7

=490km

hello from mrbilldoesmath!

answer:

a(n) - a(n-1) -3

discussion:

this ones a bit interesting. given a(n) = 5 - 3n consider this:

a(n-1) = 5 - 3(n-1)

          = (5 - 3n) + 3             => but a(n) = 5 - 3n, the first term

          = a(n)   + 3                 => subtract 3 from both sides

a(n-1) -3 = a(n)  

or

a(n) - a(n-1) -3

you,

mrb