340:2x5-(321:3+290x3-784:4)= 170x5-(107+870-196)= 850-(977-196)= 850-781=69

340:2×5-(321:3+290×3-784:4)= 340:2×5-(312:3+870-784:4)= 340:2×5-(104+870-196)= 340:2×5-(974-196) 340:2×5-778= 340:10-778= 788-34=754