For 7ii, a secant and cosine graph has been drawn. Secant is the reciprocal of cosine. Since question is asking for answers in degrees from 0 to 360, answers should be in degrees. So cos(x)=-1/3 and you may solve for the answer. Sec(x)=0.5 has no solution. For 9a, apply logarithmic laws. For 9b, try to make it 5^x in order to solve. In this case, there is one 5^x in 90^x because 90^x=(5*18)^x =5^x*18^x.