What is 4,278,649 rounded to the nearest 100

Arianna is buying plants for her garden. she buys 15 flowering plants for $96. pink flowering plants sell for $8, and purple flowering plants sell for $5. how many pink flowering plants did arianna buy? i figured out the answer! the answer is 7. 8x +5y = 96 plug in 7 for x 8 (7) + 5y = 96 56 + 5y = 96 subtract 56 from both sides 5y/y = 40/5 y = 8 she bought 7 pink and 8 purple plants

Can someone me and do the problem plz so i can understand it more better

Hardest math question of all time can you solve the equation. check for extraneous solutions.9∣9-8x∣ = 2x+3