По действиям 70*6+80-540:5; 340+60-320:8*4; 340*2-480:4

70*6+80-540:5 = 312

1) 70*6 = 420

2) 540:5 = 108

3) 420-108 = 312

340+60-320:8*4 = 390

1) 8*4 = 32

2) 320: 32 = 10

3) 340+60 = 400

4) 400 - 10 = 390

340*2-480:4 = 560

1) 340*2 = 680

2) 480:4 = 120

3) 680 - 120 = 560