X^2-10x+31=0 solve by completing the square

Which of these is and example of a literal equation? a) 6+30=6^2 b)3x-4y c)12=9+3x d)ax-by=k

The marked price of an article is 25% above its selling price and the cost price is 30% less than its marked price . find the discount percent and gain percent. only a brainlest can solve it i will mark you brainlest

Alex measured the length of an item to be 3.7 cm. the actual length is 3.5 cm. what is alex’s percent error?