ANSWER
[tex]\cos(y) = \frac{4}{5} [/tex]
EXPLANATION
From the mnemonics SOH-CAH-TOA.
We want to find the cosine of y
CAH means cosine ratio involves adjacent over the hypotenuse.
[tex] \cos(y) = \frac{adjacent}{hypotenuse} [/tex]
From the right by triangle, the side ajacent to angle y is 64 units and the hypotenuse is 80 units.
[tex] \cos(y) = \frac{64}{80} [/tex]
[tex]\cos(y) = \frac{4}{5} [/tex]
