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Slope: 3, y-intercept: 4, equation: y = 3x + 4
The sum of the first n odd numbers is n squared! So, the short answer is that the sum of the first 70 odd numbers is 70 squared, i.e. 4900.
Allow me to prove the result: odd numbers come in the form 2n-1, because 2n is always even, and the number immediately before an even number is always odd.
So, if we sum the first N odd numbers, we have

The first sum is the sum of all integers from 1 to N, which is N(N+1)/2. We want twice this sum, so we have

The second sum is simply the sum of N ones:

So, the final result is

which ends the proof.
64 dollars. 55.25 divided by .87=63.5, round to nearest dollar and you get 64 dollars
I believe the answer is B because you multiply 18 and 40 then subtract 320 from that and you will 400.