Answer:D
Step-by-step explanation:
(3x^3 - 5x^2 + 4x - 9)-(7x^3 - 8x^2 - 5x + 10)
open brackets
3x^3 - 5x^2 + 4x - 9 - 7x^3 + 8x^2 +5x - 10
Collect like terms
3x^3-7x^3-5x^2+8x^2+4x+5x-9-10
-4x^3+3x^2+9x-19
Since there are three kids, 3x3=9. 80-9=71. Danny and Mark and Evans ages combined is 71 years
Answer:
-4 +4 =0
Step-by-step explanation:
The sum of a number and its' additive inverse is 0
The additive inverse of -4 is 4
-4 +4 =0