If sinxcos(pi/7)-sin(pi/7)cosx=-sqrt2/ 2 then x can equal?

Can you simplify 4/7? 24 points will be awarded!

Maria donates a fixed amount, a, to a charity each month. if she donates $300 in 12 months, what is the equation for a? a. a + 300 = 12 b. a × 300 = 12 c. a × 12 = 300 d. a + 12 = 300 e. a + 32 = 100

In δabc, m∠acb = 90°, cd ⊥ ab and m∠acd = 45°. find: a find cd, if bc = 3 in