Plz me ill give you brainliest and 14 points just tell me what do i put in this

What is (28 + 7 + 6 + 3) x 1/2 show your work

Triangle knm is what is true about the sides of knm

Astudent was asked to find the square of 7x+3. the student quickly wrote (7x+3)^3= 49x^2+9. identify the student's error and provide the correct answer.