2( t- 7) = -4
help m plss

2-digit numbers less than 91 which are 1 less than a multiple of 10

Astudent simplified a rational expression as shown.

Which sum or difference identity would you use to verify that cos (180° - ∅) = -cos ∅? a. sin (α -β) = sin α cos β – cos α sin β b. cos (α -β) = cos α cos β – sin α sin β c. cos (α -β) = cos α cos β + sin α sin β d. sin (α + β) = sin α cos β + cos α sin β