30 * (60+а) = 4500

120-40/k=40

(300-n) / 20=9

70*x-150=60

5600 / (360/k-20) = 80

30 * (60+а) = 4500

60+a = 150

a = 150-60

a = 90

120-40/k=40

40/k = 120-40

40/k = 80

k = 80:40

k = 1/2

(300-n) / 20=9

300-n = 180

n = 300-180

n = 120

70*x-150=60

70x = 60+150

70x = 210

x = 3

5600 / (360/k-20) = 80

360/k-20=5600/80

360/k-20 = 70

360/k = 70+20

360/k = 90

k = 360/90

k = 4