Answer:
3135
Explanation:
Givens
a1 = 6
Use t4 - t3 to get d
t4 = 27
t3 = 20
Step One
Find a1 and d
a1 = 6
d = t4 - t3
d = 27 - 20
d = 7
Step Two
Find the 30th Term
tn= a1 + (n -1 )*d
t30 = 6 + (30 - 1) * 7
t30 = 6 + 29*7
t30 = 6 + 203
t30 = 209
Step Three
Find the sum using Sum = (a + t30)*n/2
n = 30 given
a1 = 6 given
t30 = 209 calculated from step 2
Sum = (a1 + t30)*n/2 Substitute
Sum = (6+ 209)*30/2 Combine like terms and divide by 2
sum = 215 * 15 Multiply
Sum = 3135 Answer