What is d of the arithmetic sequence for which a5=24 and a9=40?

In arithmetic sequences, we know that they always differ by the same amount. That mean we can clearly construct them by incrementing our common differences. Let , that means going from 1 to 5, 1 non inclusive, would give us 4 more common differences, and going from 5 to 9, 5 non inclusive, would give us 4 again. That means:

Giving a_5 and a_9 numerical values then solving for d:

I subtracted the top equation from the bottom one if that isn't clear. With that, we are done.

341

step-by-step explanation:

all you have to do is 9x31 (which equals 279) and then 20x31 (which equals 620). then you have to subtract. 620-279=341.