I am assuming that the correct equation is 5(-3.4k - 7) + (3k 21) to get the sum.
distribute multiplication:
5(-3.4k) - 5(7) + (3k*21) = 0
-17k - 35 + 63k = 0
Look for k:
-17k + 63k = 35
46k = 35
46k / 46 = 35 / 46
k = 0.76
Substitute k with 0.76
5(-3.4k - 7) + (3k21) = 0
5[(-3.4)(0.76) - 7] + [{(3)(0.76)}21] = 0
5(-2.584 - 7) + (2.28)(21) = 0
5(-2.584) - 5(7) + 47.88 = 0
-12.92 - 35 + 47.88 = 0
- 47.92 + 47.88 = 0.04
