Question

help me to find the answer​

Answer 1

Answer:

635.

Explanation:

I hope it is right.

We know that, Tₙ = a + (n-1)d. and Sₙ= (n/2) {2a + (n-1)d}.

So, here-

T₁₂ = a + (12-1)d       -(1)

And,

S₁₂ = (12/2) {2a + (12-1)d}                -(2)

By solving equation (1) and (2)-

a= -40 and d= 23.

And again,

S₁₀ = (10/2) {2a + (10-1)d}

By putting the values obtained-

S₁₀ = 635.