m parallel lines cut n parallel lines giving rise to 60 parallelograms. What is the value of (m+n) ?

Step-by-step solution

Number of parallelogram = ^m C₂ ^n C₂ ^m C₂ ^n C₂=60 m(m-1) 2 n(n-1) 2 =60m(m-1) n(n-1)=240 By observation, m(m-1)=20=5 4n(n-1)=12=4 3m=5, n=4m+n=9