Choose one development in field of biology and discuss its contributions ro human​

your best option is 5,000 kg

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)

ask your friends for what they got then copy it down if you don't have any friends which is fine than google it or pay the teacher