how can you use a number line to determine which value is greater when two or more integers are being compared

Find the value of the cosine for angle a

Can someone me do math because i am having a breakdown rn because i don’t get it

Tim's phone service charges $26.39 plus an additional $0.21 for each text message sent per month. if tim's phone bill was $31.64, which equation could be used to find how many text messages, x, tim sent last month?