Can someone me for this question? i want to know how i can solve this question pls?

What is the length of the segment joining the points at (4,5) and (6,-2) round to the nearest tenth if necessary

Suppose a pendulum is l meters long. the time, t,in seconds that it tales to swing back and forth once is given by t=2.01

Jack did 3/5 of all problems on his weekend homework before sunday. on sunday he solved 1/3 of what was left and the last 4 problems. how many problems were assigned for the weekend?