Step-by-step explanation:
t8 = a1 + (n - 1)*d
t8 = 17
17 = a1 + 7*d
t12 = 25
25 = a1 + 11d
17 = a1 + 7d Subtract
8 = 4d Divide by 4
8/4 = 4d/4
2 = d
17 = a1 + 7d
17 = a1 + 7*2
17 = a1 + 14 Subtract 14
3 = a1
Sum 20 terms
The 20 term = a1 + 19*2
The 20 term = 3 + 38
= 41
Sum = (a1 + a20) * 20 / 2
Sum = (3 + 41)* 20/2
Sum = 44 * 10
Sum = 440
Answer:
10
Step-by-step explanation:
The answer is 10 because there are 20 days and no home work is due on 7 of those days so that’s 13 days with homework from math or writing. Then you take the three days where it was just math and subtract that to get 10 days of writing.
Answer:
14x=4-21y
Step-by-step explanation:
