To clear the fractions we multiply both sides by the least common multiple of all the denominators.
1/2 x + 2/3 = 4
Denominators 2 and 3, so multiply both sides by [Answer]: 6
3/4 x + 1 = 5/6
Denoms 4 and 6, LCM=12 Answer: 12
6/7 x - 2/3 = 5/21
LCM(7,3,21)=21 Answer: 21
3/5 + x/2 = 9
LCM(5,2) Answer: 10
25/4 = 6 + 1/2 x
LCM(4,2) Answer: 4
