Question

-3,-7,-11..... Can we find a30-a20 without actually u

Answer 1

a30=a+29d

a=-3,d=-4

so,

a30 =-3+29(-4)

=-3+(-116)

=-3-116

=-119. a30=119

now a20 = a+19d

=-3+19(-4)

=-3-76

-79

so, a30-a20=-119-(-79)

=-119+79

=-49

hope this has helped you