Answer:
a) k = 10 b) k = 7.5
Step-by-step explanation:
a)
( 5k+ 20 ) + ( 7k + 40 ) = 180
12k + 60 = 180
12k = 120
k = 10
b)
40 + ( 12k + 10) + 180 - ( 8k + 80 ) = 180
50 + 12k + 180 - 8k - 80 = 180
50 + 12k -8k - 80 = 0
50 + 4k - 80 = 0
30 = 4k
k = 7.5
