I have like a few really basic but idontknow how to solve questions. hope someone can help! thanks in advance! ^^
4) Initially 2 particles A and B are 480cm apart. Particles A and B then move towards each other at speed of 15cm/s and 25cm/s. Find the number of seconds that had elapsed before collision takes place
5) The sum of 3 of the exterior angles of a 7-sided polygon is 200 deg. Find
i) the sum of the three interior angles corresponding to the three exterior angles
ii) The sum of the remaining four interior angles
6) A group of pupils is practising their march past.
If they march in pairs, one pupil is without a partner.
If they march in 3s, 5s, or 7s, there is one pupil short.
Calculate the smallest possible number of pupils in this group.