n = 20
d = 6
a = 4
L = a + (n - 1)*d
L = 4 + (20 - 1)*6
L = 4 + 19*6
L = 118
Sum = (a + L)*n/2
Sum = (4 + 118) * 20/2
Sum = 122 * 10
Sum = 1220
Answer: number 3 4 5
Step-by-step explanation:hope this helps!
Answer:
876
Step-by-step explanation:
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