Why the multiplication of two negative numbers is positive?

3x 4=5x 8

As observed from top of a 60m hung lighthouse from the sea level, the angle of depression of two ships are 30° and 45° . If one ship if exactly behind the other on the same side of the lighthouse, find the distance between two ships

find the if factor of diff equation ( 1-y^2 ) dx/dy +xy = ay

|x2/1+x3

If x^3+y^3=t-1÷t and x^6+y^6=t^2+1÷t^2

solve it Pls

cyclic ||gm is a traeium