PEMDAS
5(7+23)
5(30)
150
Hope this helped :)
LW = 45
L + 2W = 19
L = 19-2W
substituting for L :-
W(19-2W) = 45
-2W^2 + 19W = 45
2W^2 - 19W + 45 = 0
W = 5 or 4.5
If W = 5, L = 9
If W = 4.5, L = 10
So there are 2 possible answers.
Look at intersecting points of line on x- and y-axis.
The points would be: (8,0) & (0,4)
formula of slope = (y2-y1) / (x2-x1)
(4-0)/(0-8) = -4/8 = -1/2.