2a+31
What is the value of a

Agrain trader buys the following amounts from three suppliers: 3,200 pounds, 5,100 pounds and 700 pounds. what is the total weight of his purchase?

Can someone me immediately, this is due by midnight! if you can't see the question, i'll text it to you. show the steps you took to get your answer.

Will mark brainliest! ( explain the answer too, it can be one sentence)