What words are accepted without proof in a logical system

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

2y= 3 2 x−2 y = − 1 3 x + 1 y=− 3 1 x+1

Factor k2 - 17k + 16. a.(k - 2)(k - 8) b.(k - 1)(k + 16) c.(k - 1)(k - 16)