Solve the following inequality: $21+7x\ge21$21+7x≥21
Solve the following inequality: $3x+27>3$3x+27>3
Solve the following inequality: $6x-54\ge30$6x−54≥30
Solve the following inequality: $3n-9>9$3n−9>9
Use variables to represent quantities in a real-world and mathematical problem, and construct simple equations and inequalities to solve problems by reasoning about the quantities.