Pls answer quickly and right for 17 points

Solve for x and select the correct answer

Which expression is equivalent to (5x^7+7x^8) − (4x^4−2x^8)? a. 9x^8 + 5x^7−4x^4 b. 3x^8 + 7x^7 c. 12x^8 − 2x^4 d. 5x^8 + 5x^7 + 4x^4

There are three grizzly bears in the city zoo. yogi weighs 400.5 pounds, winnie weighs 560.35 pounds, and nyla weighs 628.29 pounds. what is the average weight of the three bears? (hint: what do they weigh all together? ) a. 502.97 pounds c. 604.38 pounds b. 529.71 pounds d. 794.57 pounds