M= slope B = y intercept
So the 4 would be the slope and the -5 would be the y intercept
0.9=0.9/1=9/10=90/100
0.91=0.91/1=9.1/10=91/100
9/10=90/100
90/100<91/100
the greatest is 91/100 or 0.91
Pi≈3.14
halved we get about 1.57
so close to 1.5
depends on how exact you want it
if you want more places it is about 1.5707963267948966192313216916398
If you subtract 2x from each side you get 5x-0.15=0.6 because the subtraction of 2x on the right of the equal sign cancels out. Then, if you add 0.15 to both sides you will get 5x=0.75. Finally, if you divide both sides by 5 you get x = 0.15.
I would like to say that it was an absolute honor helping you!!