Y=10 because on the left X has to equal 30 in order for the angle to be 90 degrees. After that you take the X which is 30 and put it in the equation (2X+3Y) Now the line is a line which means that the angle containing (2X+3Y) must equal 90 like this (2X+3Y)=90 So plug in X [2(30)+3Y]=90 60+3Y=90 subtract the 60 and you get 3Y=30 divide 30 by 3 and you get Y=10 Hope this helped
