I forgot how to do this. Help me plz

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

Select the correct answer. given: ∆abc with prove: statement reason 1. given 2. ∠cab ≅ ∠edb ∠acb ≅ ∠deb if two parallel lines are cut by a transversal, the corresponding angles are congruent. 3. ∆abc ~ ∆dbe aa criterion for similarity 4. corresponding sides of similar triangles are proportional. 5. ab = ad + db cb = ce + eb segment addition 6. substitution property of equality 7. division 8. subtraction property of equality what is the missing statement in the proof? scroll down to see the entire proof.

How to find the volume of an area and height