Aboat moves at a speed of 15 km/h in still water. the river it is traveling in flows at a rate of 3 km/h downstream. what is the velocity of the boat if it travels downstream? what is the velocity of the boat if it travels upstream

When boat travels downstream the two velocities add up to give the answer 15+3=18km/hr. 
When boat travels upstream the velocity of river gets subtracted from velocity of boat which gives the result as 15-3=12km/hr.

Hope I helped :)

a long strand of spaghetti is folded once. if this is cut 20 times, how many pieces of spaghetti will there be? a long strand of spaghetti is folded once. if this is cut 20 times, how many pieces of spaghetti will there be? a long strand of spaghetti is folded once. if this is cut 20 times, how many pieces of spaghetti will there be? a long strand of spaghetti is folded once. if this is cut 20 times, how many pieces of spaghetti will there be? a long strand of spaghetti is folded once. if this is cut 20 times, how many pieces of spaghetti will there be?

\