(7 + x - 9/24) × 40 = 480

7 × 40 + 40x - 9/24 × 40 = 480

280 + 40x - 9/24 × 40/1 = 480

280 + 40x - 9/3 × 5/1 = 480

280 + 40x - 45/3 = 480

40x = 480 - 280 + 45/3

40x = 200 + 15

40x = 215

x = 215/40

x = 43/8

х=5,375