Give first the step you will use to seperate variable and then solve the equation:
a)z/3=5/4​

Option #1 (and the fastest):
Multiply both sides by 3 to cancel the “divided by 3” on the left side where z is.
z/3 • 3 = 5/4 •3

z = 15/4

Option #2: Cross multiply and then solve for z:
z/3 = 5/4 -> 4z=15

Then divide by 4.
4z/4 = 15/4

z = 15/4

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