7*3+/28+8/:6*5 = 4*/18:9/*7-64:8 = 80-/25:5+9:2-13 = 2*9-36:/3*8:6 / = 4*4:2+/30-15/:3=

7 * 3 + (28 + 8) : 6 * 5 = 51.

1) 28 + 8 = 36;

2) 7 * 3 = 21;

3) 36 : 6 = 6;

4) 6 * 5 = 30;

5) 21 + 30 = 51.

4 * (18 : 9) * 7 - 64 : 8 = 48.

1) 18 : 9 = 2;

2) 4 * 2 = 8;

3) 8 * 7 = 56;

4) 64 : 8 = 8;

5) 56 - 8 = 48.

80 - (25 : 5) + 9 : 2 - 13 = 6 3/26.

1) 25 : 5 = 5;

2) 9 : 2 = 4,5;

3) 80 - 5 = 75;

4) 75 + 4,5 = 79,5;

5) 79,5 : 13 = 79 5/10 : 13 = 795/100 * 1/13 = 795/130 = 159/26 = 6 3/26.

2 * 9 - 36 : (3 * 8 : 6) = 16.

1) 3 * 8 = 24;

2) 24 : 6 = 4;

3) 2 * 9 = 18;

4) 36 : 18 = 2;

5) 18 - 2 = 16.

4 * 4 : 2 + (30 - 15) : 3 = 13.

1) 30 - 15 = 15;

2) 4 * 4 = 16;

3) 16 : 2 = 8;

4) 15 : 3 = 5;

5) 8 + 5 = 13.