Question

 

a+d(m+n)-d=0
a+d(m+n-1)=0 
Can u explain this step

Answer 1

a + d(m+n) - d = 0
=> a + dm + dn - d = 0   "Take d common in last three expressions"
=> a+ d(m + n -1) = 0

Answer 2

a+d(m+n)-d=0
a+dm+dn-d=0
a+d(m+n-1)=0
Hence proved