Answer:
24
Step-by-step explanation:
Positive: 690
Negative: -30
They both are complementary angles i.e their sum must equals 90°
4x+ 31 + 6x + 39 = 90
10x + 70 = 90
10x = 90-70
10x = 20
x = 2
we have to find angle ADC
just put the value of x in that expression for that angle.
angle ADC = 6x + 39 = 6 (2)+39 = 12 + 39 = 51°
Hey!
First, let's write the problem.

Multiply

with

.

Subtract

from both sides.


Divide both sides by

.


Let me know if you have any questions regarding this problem!
Thanks!
-TetraFish
NO.....9.66% less than $18,000 is $16,261.20
230×12= $2,760