30th term of the A.P: 10, 7, 4, …, is

A.P. = 10, 7, 4, …
First term, a = 10
Common difference, d = a₂ − a₁ = 7−10 = −3
As we know, for an A.P.,
a_n = a +(n−1)d
Putting the values;
a₃₀ = 10+(30−1)(−3)
a₃₀ = 10+(29)(−3)
a₃₀ = 10−87 = −77