Using all numbers:
1. (84:2):6=7; {here 84:2=42, 42:6=7}
2. 8-(6-4):2=7; {here 6-4=2, 2:2=1, 8-1=7}
3. (8:2):4+6=7; {here 8:2=4, 4:4=1, 1+6=7}
4. (8:4):2+6; {here 8:4=2, 2:2=1, 1+6=7}
Using not all numbers:
1. (8+6):2=7; {here 8+6=14, 14:2=7}
2. 6:2+4=7; {here 6:2=3, 3+4=7}
3. 42:6=7;
4. 28:4=7.
