So basically you need to figure out what adds up to the 87. so use L, or 50. now XXX=30. so now you have 80 so we still have 7 left over, so we can write 7 I's or a 5, (V) and two I's. We should use the V and the I. So we take one V, or 5. and two I's which together is 7. which leads us too LXXXVII. also always remember to have the biggest number first, in this case the L (50).
