Multiply the numbers being added then add the first number. 4X1=4, 4+1=5.
2X5=10, 10+2=12. 11X8=88, 88+8=96. I'm not sure how to get 40, though.
Hope I could help.
You have the right answer. n + p = m because inside angle + inside angle = outside angle.
Y = 5 x 3 + 8
y = 15 + 8
y = 23
