Answer:

1/4

Step-by-step explanation:

d = a₂ - a₁

d = 13/4 - 3

d = 1/4 or 0.25

a₂ = 3 + 1/4 = 13/4

a₃ = 13/4 + 1/4 = 7/2

a₄= 7/2 + 1/4 = 15/4

1/4

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