The answer is Y = 63
Here's how I got my answer:
Step 1: Add 4 to both sides. Which leaves us with [tex] Y/7 = 5 + 4 [/tex]
Step 2: Simplify [tex] 5 + 4 [/tex] to 9. Which leaves us with [tex] Y/7 = 9 [/tex]
Step 3: Multiply both sides by 7. Which leaves us with, your answer, Y = 63