Please help me solve for u. Need help fast! Thanks to whoever answers. I’ll mark the first as brainliest

Answer: u= -2/21
Step-by-step explanation:
>-14/42 - 21/42u = -12/42 (LCM of 42)
>-21/42u =2/42(Add 14/42 to both sides)
>u=-2/21 (divide both sides by -21/42, which is same as multiply both sides by -42/21)