Please help and explain.

Will give brainliest sum of arithmetic series (sigma notation) find the numerical answer to the summation given below. (image shown below)

Aconstruction worker has rope 9 m long he needs to cut it in pieces that are each 3 /5 m long how many such pieces can he cut without having any rope leftover?

One number is 4 less than 3 times a second number. if 3 more than two times the first number is decreased by 2 times the second number, the result is 11. use the substitution method. what is the first number?