A number is multiplied by 4. That result is added to 12. The final number is 40 , what is the oringial number

Factorize: x^2+8x+10 i just solved it but i don't know if the process is correct

The length of the line segment joining the midpoints of sides ab and bc of the parallelogram abcd is 10. find the length of diagnol ac

Astudent showed the steps below while solving the inequality |x-4|< 1 by graphing.