Please help me to do this

sinx+cosx-sin(x-30)+cos(x-30)=√6c os(x-15)

What is the missing step in this proof ?

Two times a number plus three times another number equals 4. three times the first number plus four times the other number is 7. find the numbers

Asquare has a side that measures 11 units. what is the area of a circle with a circumference that equals the perimeter of the square? use 3.14 for π, and round your answer to the nearest hundredth. 1519.76 units2 379.94 units2 616.56 units2 154.14 units2