Help me please im not good with rounding decimals

Solve 3x-18=2y and 5x-6y=6 by elimination show work

Adriana had a garden where he measured the height of a corn plant. what. on the first day,it was 145 cm tall.after 2 weeks is grew by 23 cm.what is the height of the corn plant

Acompany that makes? hair-care products had 5000 people try a new shampoo. of the 5000 ? people, 35 had a mild allergic reaction. what percent of the people had a mild allergic? reaction?