What value of c makes the equation true? 15 + c - 1 = 23

A = 7
B = 37
C = 14
D = 9

Identify the type of observational study described. a statistical analyst obtains data about ankle injuries by examining a hospital's records from the past 3 years. cross-sectional retrospective prospective

In trapezoid abcd, ac is a diagonal and ∠abc≅∠acd. find ac if the lengths of the bases bc and ad are 12m and 27m respectively.

Could somebody me with this radical simplification?