Solution:
[tex]1.8 + 3.5y + 0.9 + 9 = 16.2[/tex]
subtracting 0.9 and 9 from both side
[tex]1.8 + 3.5y + 0.9 + 9 - 0.9 - 9 = 16.2 - 0.9 - 9[/tex]
it will become
[tex]1.8 + 3.5y = 6.3[/tex]
subtracting 1.8 from both side
[tex]1.8 + 3.5y - 1.8 = 6.3 -1.8[/tex]
it will become
[tex]3.5y = 4.5[/tex]
now dividing both side by 3.5
[tex]\frac{3.5y}{3.5} = \frac{4.5}{3.5}[/tex]
So
[tex]y= \frac{4.5}{3.5}[/tex]
which means
[tex]y = 1.28[/tex]
Hope it helps!